mobile graphics

ok so I’m finally making my first mobile game using unreal engine 4 but I have one question before I start. what level of graphics can mobile handle. can I make the graphics like gta v level but put it on mobile or should I tone it down a little? it’s mostly for newer iPhones. is this a good idea or will my device overheat?

Technically, GTAV should be able to run on today’s phones since it originally came out on Xbox 360 and PS3 which are much less powerful than the phones we have now.
But–there are no phone games at that level of complexity, so don’t try to go for something like that.
Look at the games that are already on phones and that’s the level of quality you can shoot for.