IPhone Software idea

Hello, I’m Ali a dad of twin girls which are 1 years old. They love Apple 🍏. iPads, iPhones what ever they can get their hands on. However whenever I put on a video they start scraping the screen and within seconds they’ve changed the vidoe or got onto my calls list or even worse tapping away on my eBay app. So I was wondering why no set up a lock button. Even on accessibility the way you can put a Home Screen button on your phone but set a lock button instead. So once a vidoe or something is playing press the lock button so that kids aren’t able to get off the screen. Let me know… your 💭 Ali