How to remove the redirect to the main domain for its aliases in WordPress

For multisites, the case of creating site mirrors that open the contents of the main site is relevant.

By default, all mirrors are redirected to the main domain. To disable it, you need to add two lines at the end of the wp-config.php file:

define('WP_SITEURL', 'https://' . $_SERVER['HTTP_HOST']);
define('WP_HOME', 'https://' . $_SERVER['HTTP_HOST']);

If the site works via http, then use http instead of https.