Not yet because developers needs to app some minor coding (as was mentioned in the Apple presentation with Slide Over) to support e.g. Slide Over and PIP.
The developers need to add some coding to their apps to support PIP. As was mentioned in the Apple presentation Twitter did it in a few minutes to support Slide Over i don't know if it is also so easy with PIP.
Thanks! I just wanted to make sure of if third party apps potentially could have this feature.