Add specific CSS class to form elements from the address field
You can use the hook_form_FORMID_alter in order to add classes to the fields you want to.

/**
* Implements hook_form_FORM_ID_alter();
*/
function hook_form_FORM_ID_alter(&amp;$form, \Drupal\Core\Form\FormStateInterface $form_state, $form_id) {
  $form['my_custom_field']['#attributes']['classe'][] = "my-custom-class"
}