Get Webform pages from a Webform Submission

      $sid = 689
      $webform_submission = \Drupal\webform\Entity\WebformSubmission::load($sid);
      $webform = $webform_submission->getWebform();
      $webform_pages = $webform->getPages();

      $num_pages = count($webform_pages);
      $index = 1;
      foreach ($webform_pages as $key => $value) {
        if ($current_page === $key){
          $percentage = $index / $num_pages * 100;
          $variables["output"] = t("Completado al " . (int)$percentage . "%");
        }
          $index++;
      }