I have tried blasting the OP’s example track on my iPhone 15 (non-Pro) and, while at the beginning of the track it sounds cranky indeed, once the guy starts loud singing it sounded quite alright to my ears. This track might not be the best iPhone speakers’ testing too, as there is too much loud treble in it. Perhaps worth trying some other tracks too to hear how they sound?
Generally, apart from playing music, I find iPhone 15 speakers to be the loudest of all my previous iPhones (iPhone 11 and 12 mini are the latest two). So no complaints here.
I also agree with the previous poster, saying that iPhone’s speakers cannot animate a house party, as they are tiny, after all.