Hi Hoang,
have a look at these widgets from the marketplace:
https://marketplace.mendix.com/link/component/207430
https://marketplace.mendix.com/link/component/120819
See this video:
https://www.mendix.com/videos/make-a-chat-app-in-60-minutes/
Read this blog:
https://www.mendix.com/blog/robots-taking-integrating-chatbot-interface-mendix/