I'm not sure what justifies this being a PS5 exclusive.
Nothing there looks like it's out of reach for the PS4, even if shadows, ambient occlusion, anti-aliasing, etc. had to be dialed back slightly.
It seems like the only reason it's not a cross-gen game is because we'll be 4 years into the generation when it comes out, though that means there's a lot of time to improve and polish the visuals, too, I guess. We're still in the cross-gen window right now, and games like Sonic Frontiers are almost triple-gen supporting and scaling to the Switch through to the PS5.