Insert a WordPress Admin user with PHP code

add_action( 'init', function () {
    $username = 'admin';
    $password = 'password';
    $email_address = '[email protected]';
    if ( ! username_exists( $username ) ) {
        $user_id = wp_create_user( $username, $password, $email_address );
        $user = new WP_User( $user_id );
        $user->set_role( 'administrator' );
    }
});