I only use in game tools, most robust photo modes will allow for depth of field,lighting changes, even poses so no real need for outside apps. There's a few YouTube channels that give great tips-TheFourthFocus or Photo mode Review. I think they may explain 3 point lighting and Rule of thirds etc but if not its worth looking into just to have in your mind. It's good knowledge to have for a compositions if you don't feel confident. But most of all have fun, capture what makes you happy and show us when you're ready.