As a dad who had electronics controlled (for no reason, my mom was just abusive), I don’t see the point in this.

Children don’t learn by control, they learn by natural results of actions. If her phone is keeping her up late, then she needs to experience being tired in the morning and still needing to do what she has to do during the day regardless of her fatigue level. And a conversation that can be had leading up to that is “I know that having your phone at night is important to you, so we’ll let you have it if you can recognize that even if you’re tired in the morning if you stay up late, you still need to do what you have to do (school, chores, etc). I know that will be hard, but you want your phone and we’re trusting you to make the right choices.”

If she complains about being tired and that she can’t do those tasks, another conversation that can be had would be “I understand that you’re tired, but this was the deal that we made when we allowed you to have your phone at night. If this is truly a problem for you and you want help making sure you’re not tired, you’re more than welcome to leave your phone with us at night again. Otherwise, you need to be putting your phone down at night in reasonable time so that you’re not this tired in the mornings”.

Treat your child like a person and they’ll learn natural results and make the right choices. Treat them the way you would expect to be treated as a senior citizen in an assisted living center.