Tie down authors to see only their own posts on WordPress

tie_down_authors.php

<?php
/**
 * Tie down authors to see only their own posts
 * @package LetsGodev\MuPlugins
 * @since 1.0.0
 */
add_filter( 'pre_get_posts', 'tieDownAuthors' );

/**
 * Tie down authors to see only their own posts
 * Role:
 *      Administrator
 *      Editor
 *      Author
 *      Contributor
 *      Subscriber
 * @param WP_Query $query
 * @return WP_Query
 */
function tieDownAuthors( WP_Query $query ): WP_Query {
	global $pagenow;
	
	// If the user is on the posts list page
	if ( ! $query->is_admin || 'edit.php' !== $pagenow || $query->get('post_type') !== 'post' ) {
		return $query;
	}
	
	// If the user can the capability to edit other posts
	if ( current_user_can( 'edit_others_posts' ) ) {
		return $query;
	}

	$query->set( 'author', get_current_user_id() );
	return $query;
}