Modified wp-config.php file. This is the template. Copy to wp-config.php and adjust as needed.

wp-config.tmpl.php

<?php
/**
 * The base configuration for WordPress
 *
 * The wp-config.php creation script uses this file during the
 * installation. You don't have to use the web site, you can
 * copy this file to "wp-config.php" and fill in the values.
 *
 * This file contains the following configurations:
 *
 * * MySQL settings
 * * Secret keys
 * * Database table prefix
 * * ABSPATH
 *
 * @link https://codex.wordpress.org/Editing_wp-config.php
 *
 * @package WordPress
 *
 * File: wp-config.php
 * Created: 2019-04-01
 * Updated: 2019-06-21
 * Time: 21:16 EDT
 */

/** Default: false (when true, requires {wp-content}/advanced-cache.php). */
define( 'WP_CACHE', true );

/** Post type (Default: post). */
define( 'WP_POST_TYPE', 'post' );

/** MySQL hostname */
define( 'DB_HOST', 'localhost' );

/** Database Charset to use in creating database tables. */
define( 'DB_CHARSET', 'utf8mb4' );

/** The Database Collate type. Don't change this if in doubt. */
define( 'DB_COLLATE', 'utf8mb4_unicode_ci' );

/** Example: 'en-CA'  Used in the HTML Page. */
define( 'SITE_LANG', 'en-CA' );

/** Default: UTF-8 (Used in the HTML Page) */
define( 'SITE_CHARSET', 'UTF-8' );

/** Used in the browser tab and site header. Default Below. */
define( 'SITE_TITLE', 'Site Title' );

/** Tagline. Used in site header. Default Below. */
define( 'SITE_DESCRIPTION', 'Site Description' );

/** Default: false */
define( 'SITE_CSS_FONTS', 'Libre+Baskerville|PT+Sans' );

/** Location of the core directory, from the root. */
define( 'SITE_CORE_DIR', '/e/5.2.1' );  // Empty if WordPress core is in root.

if ( ! defined( 'SITE_ROOT_PATH' ) )
{
  /** The root of the site (not the core files). Required. */
  define( 'SITE_ROOT_PATH', rtrim( __DIR__, SITE_CORE_DIR ) );
}

/** {wp-content} is a catchall "bin", thus the term here. */
1 ? define( 'SITE_BIN_DIR', '/b' ) : ''; // Default: /b

/** For images, video, audio, PDFs, etc. Keep /uploads for now. Try /media. */
1 ? define( 'SITE_MEDIA_DIR', '/uploads' ) : '';

/** For required plugins (must use).  */
1 ? define( 'SITE_REQUIRED_DIR', '/required' ) : '';

/** For required plugins (must use).  */
1 ? define( 'SITE_CONFIG_PATH', SITE_ROOT_PATH . '/b/config' ) : '';

/** SITE_LOG_PATH.  */
1 ? define( 'SITE_LOG_PATH', SITE_ROOT_PATH . '/b/logs' ) : '';

/** WooCommerce Log Directory. (Overrides default).  */
0 ? define( 'WC_LOG_DIR', SITE_LOG_PATH . '/woo' ) : '';

/** Default: false */
define( 'SITE_USE_WP_HEAD', false );

/** Default: false */
define( 'SITE_USE_WP_FOOTER', false );

/** Default: false */
define( 'SITE_USE_CSS_FONTS', false );

/** Default: false */
define( 'SITE_USE_CSS_MIN', false );

/** Default: false */
define( 'SITE_USE_CSS_ALL', true );

/** Default: false */
define( 'SITE_USE_AUTO_PARA', true );

/** Default: false (true for increased security). */
define( 'DISALLOW_UNFILTERED_HTML', true );

/** Disable plugin and theme file editing for increased security. */
define( 'DISALLOW_FILE_EDIT', true );

/** Disable plugin updating and deleting for better stability and security. */
define( 'DISALLOW_FILE_MODS', true );

/** Disable core, theme and plugin updates for better stability. */
define( 'AUTOMATIC_UPDATER_DISABLED', true );

/** Disable unattended core updates for better stability. */
define( 'WP_AUTO_UPDATE_CORE', false );

/** Disable the virtual cron for imp. performance. Requires server side cron. */
define( 'DISABLE_WP_CRON', true );

/** Do not allow unfiltered uploads. */
define( 'ALLOW_UNFILTERED_UPLOADS', false );

/** Allow image edits to overwrite images for decreased file usage. */
define( 'IMAGE_EDIT_OVERWRITE', true );

/** No post revisions for better database usage. (Know what you write). */
define( 'WP_POST_REVISIONS', false );

/** Increase the autosave interval. Try 300 (seconds). */
define( 'AUTOSAVE_INTERVAL', 300 );

/** Default: 30 */
define( 'EMPTY_TRASH_DAYS', 30 );

/** Default: 60 (seconds). */
define( 'WP_CRON_LOCK_TIMEOUT', 60 );

/** Default: 40M */
define( 'WP_MEMORY_LIMIT', '40M' );

/** Last Default: 256M */
define( 'WP_MAX_MEMORY_LIMIT', '256M' );

/** This is a path, not a directory (Misnomer). */
1 ? define( 'WP_CONTENT_DIR', SITE_ROOT_PATH .  SITE_BIN_DIR ) : '';

/** Uploads directory. See note below. Takes priority. */
1 ? define( 'BLOGUPLOADDIR', WP_CONTENT_DIR . SITE_MEDIA_DIR ) : '';

/** One more poorly formatted constant (for multisite). */
1 ? define( 'UPLOADBLOGSDIR', WP_CONTENT_DIR . SITE_MEDIA_DIR ) : '';

/** Uploads directory (a directory, not a path). */
0 ? define( 'UPLOADS', SITE_MEDIA_DIR ) : '';

/** Default: 'wp-content/mu-plugins' (Must Use Plugin Directory *Stub*) */
1 ? define( 'MUPLUGINDIR', WP_CONTENT_DIR . SITE_REQUIRED_DIR ) : '';

/** Default: 'wp-content/mu-plugins' (Must Use Plugins *Path*) */
1 ? define( 'WPMU_PLUGIN_DIR', WP_CONTENT_DIR . SITE_REQUIRED_DIR ) : '';

/** Default: 'wp-content/mu-plugins' (Must Use Plugins URL) */
1 ? define( 'WPMU_PLUGIN_URL', WP_CONTENT_URL . SITE_REQUIRED_DIR ) : '';

//**** USER SPECIFIC SETTINGS BELOW THIS LINE ****//

// Credentials: local, staging, production.
if ( '127.0.0.1' == $_SERVER['SERVER_ADDR'] )
{
  /** Development: true. */
  define( 'WP_DEBUG', true );

  /** Local: http:// probably O.K. */
  define( 'SITE_PROTOCOL', 'http://' );

  /** Local value. */
  define( 'SITE_SERVER_NAME', $_SERVER['SERVER_NAME'] );

  /** The name of the database for WordPress */
  define('DB_NAME', '');

  /** MySQL database username */
  define('DB_USER', '');

  /** MySQL database password */
  define('DB_PASSWORD', '');

  /** Local: no bots, but put false anyways. */
  define( 'SITE_INDEX_ALLOW', false );

  /** ... */
}
elseif( file_exists( SITE_ROOT_PATH . '/.staging' ) )
{
  /** Staging: true. */
  define( 'WP_DEBUG', true );

  /** Staging: http:// maybe O.K. */
  define( 'SITE_PROTOCOL', 'http://' );

  /** Staging value. */
  define( 'SITE_SERVER_NAME', $_SERVER['SERVER_NAME'] );

  /** The name of the database for WordPress */
  define( 'DB_NAME', '' );

  /** MySQL database username */
  define( 'DB_USER', '' );

  /** MySQL database password */
  define( 'DB_PASSWORD', '' );

  /** Staging: Definitely want this to be false. */
  define( 'SITE_INDEX_ALLOW', false );

}
else
{
  /** Production: false. */
  define( 'WP_DEBUG', false );

  /** Production: https:// better. */
  define( 'SITE_PROTOCOL', 'https://' );

  /** Production value (include www. or subdomain.). */
  define( 'SITE_SERVER_NAME', '' );

  /** The name of the database for WordPress */
  define( 'DB_NAME', '' );

  /** MySQL database username */
  define( 'DB_USER', '' );

  /** MySQL database password */
  define( 'DB_PASSWORD', '' );

  /** Production: probably want this to be true. */
  define( 'SITE_INDEX_ALLOW', true );

}

if ( WP_DEBUG )
{
  /** Echo or dump errors to the website.  */
  0 ? define( 'WP_DEBUG_DISPLAY', true ) : '';

  /** Set to full path for WP 5.1.0+. Previous true|false. */
  0 ? define( 'WP_DEBUG_LOG', SITE_LOG_PATH ) : '';

  /** Use development versions of core CSS and JS files. */
  0 ? define( 'SCRIPT_DEBUG', false ) : '';

  /** Use the site debug log. */
  0 ? define( 'SITE_USE_DEBUG_LOG', true ) : '';
}

/** The URL to the root of the site (not the core files). Required. */
define( 'SITE_ROOT_URL', SITE_PROTOCOL . SITE_SERVER_NAME );

/** Where the core WordPress files reside, relative to site root. */
1 ? define( 'WP_SITEURL', SITE_ROOT_URL . SITE_CORE_DIR ) : '';

/** Where the site pages and posts reside (NOT the core files). */
1 ? define( 'WP_HOME', SITE_ROOT_URL ) : '';

/** Where the core WordPress files reside, relative to site root. */
1 ? define( 'WP_SITEURL', SITE_PROTOCOL . SITE_SERVER_NAME . SITE_CORE_DIR ) : '';

/** This is set to the full url, plus the '/b' directory. */
1 ? define( 'WP_CONTENT_URL', SITE_ROOT_URL . SITE_BIN_DIR ) : '';

/** Default: 'wp-content/mu-plugins' (Must Use Plugins URL) */
1 ? define( 'WPMU_PLUGIN_URL', WP_CONTENT_URL . SITE_REQUIRED_DIR ) : '';

/**#@+
 * Authentication Unique Keys and Salts.
 *
 * @link https://api.wordpress.org/secret-key/1.1/salt/
 *
 * Change these to invalidate existing cookies. This will force users to log
 * in again.
 *
 * @since 2.6.0
 */


/**#@-*/

/** Unique for each install, but same between local, staging and prodution. */
$table_prefix = 'wp01a_';

/* That's all, stop editing! Happy publishing. */

/** Absolute path to the WordPress directory. */
if ( ! defined( 'ABSPATH' ) ) {
  define( 'ABSPATH', dirname( __FILE__ ) . '/' );
}

/** Sets up WordPress vars and included files. */
require_once( ABSPATH . 'wp-settings.php' );

Note the logic used to progress from the local environment, through staging, to production.