You will not ask about things if you don't know they even exist.

Quite au contraire mon amie, you can just ask him to tell you typescript and keep prompting as you see fit. It will match your exact needs and style.

There's also a beta copilot for docs which includes typescript

https://githubnext.com/projects/copilot-for-docs

How can you prompt copilot like chat? It only does autocomplete well.

You need to have access to Copilot Chat, which is only available as an extension in VSC Insiders.