Show a Form on another page

Example :  Display user login form on a page

    $output = array();
    $output['cache']['#disabled'] = TRUE;
    $output['cache']['max_age']['#value'] = 0;

    $html = "";
    $html .= '<h2>' . date("H:i:s") . '</h2>\n';
    $html .= 'My Page';
    $output[] = [      '#markup' => $html    ];

   $form = \Drupal::formBuilder()->getForm('Drupal\user\Form\UserLoginForm');
    $output[] = ['form' => $form];

    return $output;