Consoles tend to do dynamic resolution - they'll drive the display at 4K (together with UI), but the actual rendering resolution will drop and adapt to the load. It actually looks pretty good - the UI and text keeps being sharp while you generally don't notice the resolution drop that much. Unfortunately most games lose this capability on PC, so you're stuck with blurry looking text if you have a good monitor or TV :(
The other trick they do is checkerboard rendering - the console only renders approximately half the scene each frame. The partially rendered frame is then combined with the previous one with added filtering. The result is not unlike the interlaced CRT TV rendering of 80s era consoles/micros - just with better filtering.
Again, this capability tends to disappear on PC versions of those games.
Lack of those two things means that in a lot of cases games on PC look/run worse on equivalent hardware than they do on the console :/
It works well in Forza Horizon 4. And yeah, I wouldn't mind the option for checkerboard rendering on PC. I understand purists want nothing to do with it, but hey, too many options is what PC is all about.