Block WordPRess rest api except logged user or if there is a parameter in the url

block-wprestapi-loggedonly-orbykeyword.php

<?php
       add_filter('rest_authentication_errors', function ($result) {
            if (!empty($result)) {
                return $result;
            }

            $access = is_user_logged_in();

            if ( !$access ) {
                if ( !isset($_GET['iwantthem']) || isset($_GET['iwantthem']) && $_GET['iwantthem'] !== 'yes' ) {
                    $access = false;
                } else {
                    $access = true;
                }
            }

            if ( !$access ) {
                return new WP_Error('rest_not_logged_in', 'You are not currently logged in or you don\'t have access.', array('status' => 401));
            }

            return $result;
        });