The few people that create games with ai and put the effort into it, to have a consistent style obviously do have ways to do that. And there are plenty of guides describing the techniques to do just that. As a hint, you can train models and you can keep recurring prompt modifiers. As for styles that are already in the model, it is trivial to tell the system to just use that style. That's bascially the root of a lot of ai hate and ai made fake problems. You can tell it to create a painting in the style of Van Gogh. You can tell it to have a character look like a publicly known person.
And my guess, if you start putting effort into it, there is a turning point, where you would just switch to a 3d rendering and just fiddle around with how to position your characters. This keeps the style consistent and does not label your game to be ai made.