How can I change form action in drupal 8?

In default, page not change and when my form path is `/site/drupal/page`, my form action is `<form data-drupal-selector="test" action="/site/drupal/page" method="post" id="test" accept-charset="UTF-8">`.

But I want change it to other page. How can I do this ?

** Redirect not worked, see this link: https://drupal.stackexchange.com/questions/232387/redirect-after-submit-form