Add custom woocommerce account page/tab with title, content, and endpoint slug

wc-coaches-menu-tab.php

<?php

if ( !defined( 'ABSPATH' ) ) exit;

// The "endpoint" key used to identify our custom menu.
// If you are adding multiple pages to the account menu, you would want to change this to an array or just get rid of the constant altogether..
define( 'MBC_PROFILE_ENDPOINT', 'coach-profile' );

/**
 * Add the Coach Profile link to the list of menu items in the dashboard.
 * 
 * @param $items
 *
 * @return array
 */
function mbc_register_coach_profile_account_menu_tab( $items ) {
	// Add coach profile in the second spot in the menu items list
	$items = array_splice( $items, 0, 1 ) + array( MBC_PROFILE_ENDPOINT => 'Coach Profile' ) + $items;
	
	return $items;
}
add_filter( 'woocommerce_account_menu_items', 'mbc_register_coach_profile_account_menu_tab', 20 );

/**
 * Register the Coach Profile rewrite rule, so the URL works.
 * Note: Refresh permalinks afterwards. Use flush_rewrite_rules() on plugin activation.
 */
function mbc_register_coach_profile_rewrite_rule() {
	add_rewrite_endpoint( MBC_PROFILE_ENDPOINT, EP_ROOT | EP_PAGES );
}
add_filter('init', 'mbc_register_coach_profile_rewrite_rule');

/**
 * Register the Coach Profile endpoint as a WooCommerce query var.
 *
 * @param $query_vars
 *
 * @return mixed
 */
function mbc_register_coach_profile_woocommerce_query_var( $query_vars ) {
	$query_vars[ MBC_PROFILE_ENDPOINT ] = MBC_PROFILE_ENDPOINT;
	return $query_vars;
}
add_filter( 'woocommerce_get_query_vars', 'mbc_register_coach_profile_woocommerce_query_var' );

/**
 * Change the title of the Coach Profile account page.
 *
 * @return string
 */
function mbc_coach_profile_page_title() {
	return 'Coach Profile';
}
add_filter( 'woocommerce_endpoint_'. MBC_PROFILE_ENDPOINT .'_title', 'mbc_coach_profile_page_title' );

/**
 * Display content for the Coach Profile account page.
 */
function mbc_display_coach_profile_account_page_content() {
	echo 'This is the page content!';
}
add_action( 'woocommerce_account_'. MBC_PROFILE_ENDPOINT .'_endpoint', 'mbc_display_coach_profile_account_page_content' );