Gotta disagree a bit.
Forza 7 had no problem keeping the locked 60 fps on Xbox One/One S and doing full 1080p - One can argue that GT7 on a comparable spec (so PS4 and PS4 Pro) looks better, and while some of that is subjective some isn't; I do think the LOD scaling is at fault here more than anything else, the funny thing is that if that's so, then they actually needed the lower LOD profile on all platforms, including the flagship.
Forza Horizon, while 30 fps on Xbox One (because Forza Horizon always defaulted to that) never drops a frame and didn't go dynamic res either, this to attest that one engine clearly controls LOD better than the other. Seeing one is god tier, the other suffers by comparison by not keeping the framerate locked on admittedly challenging conditions (Forza 7 allows rainy conditions as well).
It's specially "bad" to consider it also happens on PS5 (making it hard to call a "generational leap" on something so basic as to attest that the same bottlenecks still apply and tax it). Thus I feel the Gran Turismo engine is a bit dated at some points that evidently carry over from the PS3 days. It also probably commands more handmade optimizations for the devs working on it. I think they need to work on their pipeline from here on, or the distance will only get bigger.
Despite all that, it's very good looking and all the released versions are good, which is the most important. Screw the always online component though, very bad taste for a game that is sold - it's basically shareware.
Reduces image quality when it hits. I'm personally not a fan, against keeping resolution, but it's preferable to framedrops - I'm guessing they could get away with fallbacks to 900p for the most part on ps4, 1440p on PS4 pro and 1800p on PS5. I'm guessing Polyphony Digital doesn't like to do that and doesn't have expertise in image reconstruction techniques, it's not something you turn on, it's something you have to implement.
Seeing they don't keep 60 fps during gameplay at all times (even if it's not a real issue, which it really doesn't seem to be) and don't mitigate the effect kinda takes them out of the "tech" pole position. These are the guys that pulled Gran Turismo at locked 60 fps on PSP, not to mention
GT4 on PS2 at 60 fps. GT4 is still god tier in my book.