exactly. There is a difference between scaling down things such as resolution, anti-aliasing, textures etc and trying to apply that to overall gameplay mechanics/design. Certain games need to be made specifically for next gen due to the bottle necking over the older models internal structure.
so, for example, the new Ratchet and Clank, that could easily be scaled down graphically to the ps4 version (which sitll looks good) but you cannot make use of the dimension transitions of the new game due to the limited hardware of the ps4. What the ps5 is doing in the new R&C is disguising loading times with portals like how they disguise it with slow walking or crawling through cracks in other games. The difference is that the ps5 loads new zones so insanely quickl (around .2 seconds) that you don't even notice you're going through them. The ps4 cannot do the same thing.
A lot of those gameplay mechanics are gonna be prevalent with the ps5 because thats what it's main feature is, non-existent loading times which means developers can now do a lot of different things they weren't able to do before specifically on the ps5.