Option to set to Enabled by default

@drupgirl

If you want hide file access always, simply use below hook and Access controller,

/**
 * Implements hook_entity_type_alter().
 */
function your_module_entity_type_alter(&$entity_types) {
  $entity_types['file']->setAccessClass('Drupal\your_module\FileViewAccessControlHandler');
}

Access handler path: your_module/src/FileViewAccessControlHandler.php

<?php

namespace Drupal\your_module;

use Drupal\Core\Access\AccessResult;
use Drupal\Core\Session\AccountInterface;
use Drupal\Core\Entity\EntityInterface;
use Drupal\file\FileAccessFormatterControlHandlerInterface;
use Drupal\file\FileAccessControlHandler;

/**
 * Provides a File access control handler.
 */
class FileViewAccessControlHandler extends FileAccessControlHandler implements FileAccessFormatterControlHandlerInterface {

  /**
   * {@inheritdoc}
   */
  protected function checkAccess(EntityInterface $entity, $operation, AccountInterface $account) {
    // Check if the file permission exists or not.
    if ($operation == 'view') {
      return AccessResult::forbidden();
    }

    // For other operations, fall back to the parent check.
    return parent::checkAccess($entity, $operation, $account);
  }

}