The JSON API Extras module provides a user interface for additional customization. The JSON API Extras module should be added to your Drupal installation like all other modules, using Composer:
cd /path/to/drupal8
composer require drupal/jsonapi_extras
Once the module is installed in Drupal, you will have the ability to enable or disable endpoints, change resource names, alter resource paths, disable fields, alias field names, and enhance field outputs.