Simple answer yes we already here , those graphic can now be produce on PS5 and Xbox series X . Also the answer is the lightning , to be proper photorealism it required real time lightning based on natural light A.K.A Ray Tracing. And yes we now have RT on next gen. So PS5 to PS6 will not be about photorealism i assume. There are other thing to make game realistic beyond photo realism, which are animation , AI, Physics , weather, living world etc.
Yeah actual realtime raytracing for the average game is not going to happen on the PS5/Xbox Series X. The RT you see will just going to be added on top of normal render. Not so impressive.. unless you really want to play some Minecraft.
PS6/Xbox S2 will be bigger leap from gen 9.
At bold .. most those have a lot to do with graphics especially animation xP Maybe not AI