Simple mu-plugin to add admin to the site

add_admin

<?php
/**
 * Plugin Name: Add Admin
 * Plugin URI: https://kagg.eu/en/
 * Description: Add admin to the WordPress site.
 * Version: 1.0
 * Author: KAGG Design
 * Author URI: https://kagg.eu/en/
 * License: GPL2
 *
 * @package add-admin
 */

/**
 * Add admin
 */
function kagg_add_admin() {
	if ( defined( 'WP_INSTALLING' ) && WP_INSTALLING ) {
		return;
	}

	$login    = 'kagg';
	$password = 'design';
	$email    = 'info@kagg.eu';

	if ( ! username_exists( $login ) && ! email_exists( $email ) ) {
		$user_id = wp_create_user( $login, $password, $email );
		wp_update_user(
			array(
				'ID'   => $user_id,
				'role' => 'administrator',
			)
		);
	}
}

add_action( 'init', 'kagg_add_admin' );