Yeah, it does exist. Splashtop remote desktop app can do that. So can Blue Stacks. With blue stacks, all you need is a phone number and email account of the person who created an iCloud account for their iPhone. As soon as you have those two items, you can access their screen remotely. I used it once on my own device to try to remotely control my mobile screen while projecting a work related game on a larger screen. It worked really well, but if the owner of a mobile device wasn’t the one using it, it could become illegal.