Yes it does run in native 4k, did you even watch the videos you are talking about? Even the 120hz Resolution mode with VRR apparently...The game doesn't really run native in 4K, Digital Foundry on YT has great videos about that.
BTT: On one of their videos they show a comparison between PS5 PS4/PRO with the release version particle effects. I was first surprised that PS5 dropped the most, but then again, 4k and high resolution effects...
I wish they hadn't lowered these effects that hard. An adaptive resolution mode would've also been an option (or 1800p performance mode).
But in the last Manufacturer Race at Nürburgring24h in the rain it seemed like there was more effects again, than after the initial nerf.
Here's a screenshot of the comparison of consoles...ah, those were the rainy days...