I wish the App Timer was like a TV timer, where the TV just turns off after the timer is up. I'd like something that kills a certain app that is running on my

I wish the App Timer was like a TV timer, where the TV just turns off after the timer is up. I'd like something that kills a certain app that is running on my phone. It sounds like that isn't what the App Timer will do. I imagine you would need root on your phone to kill apps from another app.