getOverviewUrl example

foreach ($form_values['display_modes_custom'] as $mode => $value) {
        if (!empty($value) && empty($current_statuses[$mode])) {
          // If no display exists for the newly enabled view mode, initialize           // it with those from the 'default' view mode, which were used so           // far.           if (!$this->entityTypeManager->getStorage($this->entity->getEntityTypeId())->load($this->entity->getTargetEntityTypeId() . '.' . $this->entity->getTargetBundle() . '.' . $mode)) {
            $display = $this->getEntityDisplay($this->entity->getTargetEntityTypeId(), $this->entity->getTargetBundle(), 'default')->createCopy($mode);
            $display->save();
          }

          $display_mode_label = $display_modes[$mode]['label'];
          $url = $this->getOverviewUrl($mode);
          $this->messenger()->addStatus($this->t('The %display_mode mode now uses custom display settings. You might want to <a href=":url">configure them</a>.', ['%display_mode' => $display_mode_label, ':url' => $url->toString()]));
        }
        $statuses[$mode] = !empty($value);
      }

      $this->saveDisplayStatuses($statuses);
    }

    $this->messenger()->addStatus($this->t('Your settings have been saved.'));
  }