If you mean using same clothes for PCs and NPCs, some games do it. The Sims, Hitman games, Rimworld, many RPGs like Fallout and Skyrim.
As for the sliders, yeah. I have never seen something exactly like that. But I expect it just wouldn't fit well in most games and also wouldn't really be much of a sales point. People would always prefer just one of the settings, so it wouldn't be better than a game where it is the only option.
I can also already hear the screeching from game journalists and religious groups about adding such a slider.