Use a third-party CSS or JS Framework, a self-hosted service like a CRM, or a third-party service with the site.
Drupal Module for Emailoctopus using their API v1.6. Maintained and supported by
Convertkit integration module using API v3.
NLP Cloud provides cloud based AI tools which can be used for generating and classifying content.
The Drupal AI module provides a framework for easily integrating Artificial Intelligence on any Drupal site using any kind of AI (from multiple vendors).