/**
* Implements hook_form_FORM_ID_alter().
*/
function MODULE_NAME_form_views_exposed_form_alter(array &$form, FormStateInterface $form_state, $form_id) {
$view = $form_state->getStorage();
$view_id = $view['view']->id();
$display_id = $view['view']->current_display;
if ($view_id === 'THE_VIEW_ID' && $display_id === 'THE_DISPLAY_ID_eg:page_1') {
$form['foo'] = ['YOUR_FILTER'];
}
}