First, hello and welcome to the forum. This is the Classic Menswear thread, there is also a Streetwear&Denim thread. You might find more answers to this question if you try posting it over on that side.
Second, the amount the wallet will protrude from the back pocket will depend on a number of variables. (e.g. how large is the person, what brand and style of pants or jeans). It will be unlikely that someone can answer that unless they have the same wallet, wear the same pants and are of the same stature as you.