How to enable handtracking 2.0 on Unreal?

You could try to change the manifest file as described in the article in the link but I expect it will take a while before this is actually implemented in Unreal. In the last few years, the binary Unreal (from the launcher) wasn't always up to date with the latest Oculus plugin/features.

https://developer.oculus.com/blog/presence-platforms-hand-tracking-api-gets-an-upgrade/

The latest build of the oculus unreal branch was updated with this!
Just check it in the OculusVR plugin settings.