How to get programatically 'display_options' for a specific page in Views
Try with:

function association_exportCSV($view, $page) {
  $view = \Drupal\views\Views::getView($view);
  // $display_id in this case is  'rest_export_1
  $view-&gt;setDisplay($page);
  $path = $view-&gt;getPath();
  file_unmanaged_save_data($page, 'private://' . $path . '.csv', FILE_EXISTS_REPLACE);
}