Disable the default post type on sites that do not need it.

functions.php

<?php
/**
 * WordPress Theme constants and setup functions
 *
 * @package WPCustomTheme
 */

/*
 * When using WordPress as a CMS the Posts content type might not be useful or
 * required on some sites. While WordPress provides a way to deregister custom
 * post type, the default Post type in WordPress cannot be dergegistered or
 * disabled. It can only be hidden. A few caveats:
 *    * New posts can still be created using the direct link.
 *    * Existing posts are not affected and will continue to load publicly.
 *    * Editing exisiting posts will not be possible.
 *    * Multisite will still show a menu item to create new posts.
 */
add_action( 'wp_dashboard_setup', 'remove_draft_widget', 999 );
add_filter( 'register_post_type_args', 'remove_default_post_type', 0, 2 );

/**
 * Remove Quick Draft Dashboard Widget
 */
function remove_draft_widget() {
	remove_meta_box( 'dashboard_quick_press', 'dashboard', 'side' );
}

/**
 * Remove access to the Post type as well as hide it from the menu
 *
 * @param array  $args The array of arguments for registering a post type.
 * @param string $post_type The post type.
 * @return array
 */
function remove_default_post_type( $args, $post_type ) {
	if ( 'post' === $post_type ) {
		$args['public']              = false;
		$args['show_ui']             = false;
		$args['show_in_menu']        = false;
		$args['show_in_admin_bar']   = false;
		$args['show_in_nav_menus']   = false;
		$args['can_export']          = false;
		$args['has_archive']         = false;
		$args['exclude_from_search'] = true;
		$args['publicly_queryable']  = false;
		$args['show_in_rest']        = false;
	}
	return $args;
}