Ipad ios xcode block currently running app

I am needing to overlay a screen on top of another one in the way that it blocks the original app from being used? Or would It be possible to power off the iPad via Xcode/Swift? Reason being is that I am in need to creating an app for my own personal use at home for my kids. I am wanting to place a timer on my phone for when the power is turned off or the program they are currently using is blocked by an overlay. Since this is for my own personal use the ability to use “private” apis are just fine if there are no public apis that can currently do any of the above. Also, there would be no need to place the app in the apple App Store. I’m looking to just be able to send restful commands or http commands to a background app that’s running on the iPads and then depending on what I sent, have the iPad do it. So to list what I am trying to find code for: - way to power off/on the iPad. - have an overlay that blocks the currently running app on the iPad. - any other way I can do the above that would be better/easier but has the same outcome that I am looking for.