In 5E, I just go by the text for the spell and any scrolls anyone might happen to find (and I generally don't allow anything much greater than the effects listed). Better Wishes than that are in the realm of DM fiat.

Historically, I used to rule that a Wish is always granted by the 'nearest' wish-granting entity. Which was usually a deity of some sort, but might be a Ki-Rin or a Genie or whatever. Once you cast it, they have to grant it, but they interpreted it according to their alignment or goals or motives.

A very lawful creature will interpret the Wish precisely, an evil or chaotic creature might give you the Monkey's Paw Treatment, a Good creature might pervert the Wish if they feel it's selfish or harmful.

So on the rare occasion the players got access to a Wish, it turned into an in-game quest to work out what entity was most amenable to their interests and what they needed to do to curry favour with them, and then how to make sure the right entity is 'close by' when the Wish is cast.

The more egregious the Wish , the more favour they need to curry to ensure it goes the way they want (and, possibly, the more interest other entities might have in interfering).

It was my go-to method for years and years. I always disliked the overly adversarial "precise-wording" paradigm older editions basically mandated. So I changed it from an unresolvable OC conflict to an resolvable IC conflict, which made for good stories.