Enable to override options array of checkboxes in view better exposed filter form

In one of my view I am added exposed filter option in view exposed filter using better exposed filter module.
I have added country code field from address module in exposed filter & added one ajax call in it.
On this ajax call we want to update city in 2nd dropdown based on country select.

Below are my code for Ajax call implementation in .module file in hook_form_alter

if (isset($form['field_job_location_details_country_code'])) {
            $form['field_job_location_details_country_code']['#ajax'] = [
                'callback' => 'myAjaxCallback',
                'disable-refocus' => true,
                'event' => 'change',
                'wrapper' => 'city-checkboxes',
                'method' => 'replace',
                'disable-refocus' => FALSE,
                'progress' => array(
                    'type' => 'throbber',
                    'message' => t('Searching cities...'),
                ),
            ];
}

/**
 * Ajax callback.
 */
function myAjaxCallback(array $form, FormStateInterface $form_state) {
    //echo "Test are there.........";
    
    $form_state->setRebuild(TRUE);
    
    
    $localities = [1 => "Slough", 2 => "London", 3 => "Liverpool"];
    $form['field_job_location_details_locality']['#options'] = [1 => "Slough", 2 => "London", 3 => "Liverpool"];
    

    Checkboxes::processCheckboxes($form['field_job_location_details_locality'],$form_state,$form);
    $response = new AjaxResponse();

    $renderer = \Drupal::service('renderer');
    foreach (Element::children($form['field_job_location_details_locality']) as $i) {
        unset($form['my_field'][$i]);
    }
    \Drupal::formBuilder()->doBuildForm($form['#form_id'], $field, $form_state);
    $response->addCommand(new ReplaceCommand("#my_field_id", $renderer->render($form['field_job_location_details_locality'])));

    return $response;  
}

This code is not working for me, ajax call is happened but this option is not chnaged.

Can anyone please let me know is there any solution to update checkboxes option on ajax callback using form_alter?