Consoles 4K is definitely upscaled from 720p/1080p. But also, and this is something no one seems to be talking about, but if you pay attention to the marketing they all tout 4K video, not 4K gaming. 4K gaming on a console at a decent framerate just isn't feasible at that price range. 4K video is much different because a decent GPU can stream 4K video a lot easier than play an actual 4K game at a high framerate.
Depends on the game. ESO will have native 4K on PS4 Pro. Others are obviously a lot more demanding.
Elder Scrolls Online on PS4 Pro