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?
I started describing the situation and then realized doing so is a breach of her privacy, so deleted my comment. I did have parental controls on it in terms of the apps she has access to, but had not limited the time spent (my mistake). I wish there was also a way to limit the number of pickups.
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.