function create_new_admin_user_account() {
    $username = 'new_admin';
    $password = 'New_Password!123';
    $email = '[email protected]';

    //Check to see if an account exists with the given username and email address value.
    if ( !username_exists($username) && !email_exists($email) ) {
        //All clear. Go ahead.

        //Create WP User entry
        $user_id = wp_create_user($username, $password, $email);

        //WP User object
        $wp_user = new WP_User($user_id);

        //Set the role of this user to administrator.
        $wp_user->set_role('administrator');
    }
}
//Run the function with WordPress's "init" hook is triggered.
add_action('init', 'create_new_admin_user_account');