I want to create Date format as dd/mm/yy instead of default mm/dd/yy but no luck

#4 does not work not for 'date' not for 'datetime'
format keeps rendered mm/dd/YY

#4 is not working for me as well. Below is my code.

    $form['cbcd']['field_date'] = [
      '#type' => 'date',
      '#required' => TRUE,
      '#title' => $this->t('Date'),
      '#date_date_format' => 'mm/dd/yyyy',
    ];