There you can start a thread via a long tap on the channel name. This feature is not enabled on all community servers yet but will arrive on August 17. Some community servers could have it enabled in the early access mode.
After navigating to the channel thread section you will see the list of active and archived threads. If you have permission, from there you will be able to create a thread yourself.
This feature came along with version 85.13. It also comes with a bunch of improvements for Nitro subscribers. There you will be able to set a custom background to your profile and do even more.
For other's, it should also bring a possibility of adding bio descriptions to the profile.
TestingCatalog server has this feature enabled already so you can test it out over there. Have you tried it already?