/**
 * Implements hook_field_ui_preconfigured_options_alter().
 */
function {{ machine_name }}_field_ui_preconfigured_options_alter(array &$options, $field_type) {
  // If the field is not an "entity_reference"-based field, bail out.
  /** @var \Drupal\Core\Field\FieldTypePluginManager $field_type_manager */
  $field_type_manager = \Drupal::service('plugin.manager.field.field_type');
  $class = $field_type_manager->getPluginClass($field_type);
  if (!is_a($class, 'Drupal\Core\Field\Plugin\Field\FieldType\EntityReferenceItem', TRUE)) {
    return;
  }

  // Set the default formatter for media in entity reference fields to be the
  // "Rendered entity" formatter.
  if (!empty($options['media'])) {
    $options['media']['entity_view_display']['type'] = 'entity_reference_entity_view';
  }
}