If we want http and https at the same time, there is no problem!  We write the following in wp-config.php

function isSecure() {
return
(!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off')
|| $_SERVER['SERVER_PORT'] == 443;
}

$web_site = 'domain.gr';
$schema = isSecure() ? 'https://' : 'http://';
$web_site_url = $schema . $web_site;

define('WP_HOME', $web_site_url);
define('WP_SITEURL', $web_site_url);