Also scroll to anchor ID

In your page code

  //----- GET OTHER URL ARGUMENTS -----
  $ScrollPageToAnchorId = $_GET['scroll_to_anchor'] ?? '';

  if ($ScrollPageToAnchorId !== '')
  {
    //SCROLL PAGE TO ANCHOR
    $HtmlOutput .= <<<_END
      <script>
        document.addEventListener("DOMContentLoaded", function(event) {
          document.getElementById('$ScrollPageToAnchorId').scrollIntoView(true);
        });
      </script>
_END;
  }

To trigger it

  //Redirect to same page to clear POST
  $RedirectToUrl = parse_url($_SERVER["REQUEST_URI"], PHP_URL_PATH);    //Get page without any url arguments
  $RedirectToUrl .= "?gid=$GroupId";
  $RedirectToUrl .= "&scroll_to_anchor=MyAnchorIdName";
  echo '<script>window.location.replace("' . $RedirectToUrl . '");</script>';
  return '';