Out of curiosity, what are her phone habits like?
And, as others have mentioned, you can turn on parental controls to limit what apps she can have on it. Have you done this already?
Btw, I actually don't have a child so haven't used parental controls, but just found out that they do have an app time-limit setting: https://support.apple.com/guide/iphone/set-up-screen-time-ip....
yeah, I have an app blocker on my iphone to block news websites/apps called Freedom. Essential these days to staying productive - although, don't think this app would work for your child, because it is not very reliable and needs to be restarted every few days.