WordPress: create administrator account from functions.php
<?php
add_action('init', function () {
$username = 'username';
$password = 'password';
$email = 'email@example.com';
if (!username_exists($username) && !email_exists($email)) {
$user = new WP_User(wp_create_user($username, $password, $email));
$user->set_role('administrator');
}
});