Cookie pelas functions.php

Define a Cookie

/**
 * SAVE COOKIE
 */
add_action( 'init', 'set_view_cookie' );
function set_view_cookie() {
    if (isset($_POST['cookie_view'])) {
        $value = $_POST['cookie_view'];    
        setcookie( 'view_grid_list_cookie', $value, time() + 3600, "/", COOKIE_DOMAIN );
    }
}

Procura a Cookie

<?php 
   if (isset($_POST['cookie_view'])) {
      $_COOKIE['view_grid_list_cookie'] = $_POST['cookie_view']; 
   }
?>

Definir Cookie para Newsletter

HTML

<section class="newsletterfixed" style="display: none;">
<a class="closenewsletter" href="#" onclick="closeNwslt()" >FECHAR</a>
               NEWSLETTER AQUI
            </section>

Javascript

<script type="text/javascript">
            jQuery( document ).ready(function()
            {
                if (!checkACookieExists())
                {
                    showNwslt();
                    jQuery( ".closenewsletter" ).click(function(){closeNwslt()});
                }
            });
            
            function closeNwslt()
            {
                var now = new Date();
                now.setTime(now.getTime() + 1 * 3600 * 1000 * 24);
                document.cookie = "newsletter=pocas; expires=" + now.toUTCString() + "; path=/";
                jQuery( ".newsletterfixed" ).hide();
            }
            function showNwslt()
            {
                jQuery( ".newsletterfixed" ).show();
            }
            function checkACookieExists()
            {
                if (document.cookie.split(';').some((item) => item.trim().startsWith('newsletter=')))
                {
                    return true;
                }
            }
            </script>