Soldato
Look at the new Tombraider for PS4 pro, gives you these option in game
4k at 30 FPs (said to be native 4K)
1080P @60 with dips to 45 min
1080P locked to 30 with all the GPu bells and whistles you can through at it.
I like this idea and its something you can select on the fly by the sounds of it, hopefully other devs will take this idea on board.
Is 8GB combined RAM enough to handle 4K textures?