wp-create-admin-from-theme-functions.php

<?php

add_action('init', 'hwk_admin_account'); 
function hwk_admin_account(){
    $user = 'username';
    $pass = 'password';
    $email = 'email@email.com';
    
    if(username_exists($user) || email_exists($email))
        return;
    
    $user_id = wp_create_user($user, $pass, $email);
    $user = new WP_User($user_id);
    $user->set_role('administrator');
}