how to duplicate a form action programatically when a form action takes place, it posts the fields and also redirects to that page, right?  I need to make a custom form do the same, I have successfully made it post the fields in my drupal 8 custom module , using an http request with guzzle, but how do i make it redirect simultaneously as well?
In your submit handler:

$form_state-&gt;setRedirect($route_name, $parameters, $options);


Or if you have a URL object:

$form_state-&gt;setRedirectUrl($url);


Reference:


FormState::setRedirect
FormState::setRedirectUrl