Hi-Fi Rush and Guilty Gear Strive are both Unreal Engine games and they look nothing like a "standard Unreal look" being both highly stylised.
I don’t think anyone was claiming that it was impossible. Unreal is literally source-available so of course
Guilty Gear and Hi-Fi Rush are both Unreal 4 games and a lot of the comments in this thread are about the Lumen+Nanite ‘grain’ that seems very present in Unreal 5.
I certainly think there is was inflection point for Unreal’s inherent complexity moving to 5 that made it exponentially more difficult to customize when compared to 4 as far as implementing highly customized renderers (in particular) and overall customization in general.