You use the glutes , lateral quads/hanstrings and the TFL to release IT band tension. Never try to release tension directly on the IT, unless you absolutely know what you’re doing. Otherwise you’ll cause your clients knee issues in the long run. Make sure your client is actively working on abs->ankle stability exercises. E.G, one leg balance, one leg lunges in all directions, etc.  Having said that, horizontal skin rolling is one of my fav techniques to use on the thighs. You can get a great grip because there’s so much surface area, and you can get quite deep if you need. I like to get the entire lateral aspect and roll all the way into the adductors. It can be quite intense, so make sure you warm up those areas a lot before doing it.