We have that same problem with our 9 yo boy. We have a limit of how much time he gets on his ipad. Tv not as much but we limit that too. If we see him on either one after time is up or when he’s not supposed to it gets turned off. If there is a fight about it, then it goes away for that day or the next (depending on the time it happens). Now, is he really annoying and hyper without it? Yes. But we will offer to play games, he can play w the dog, etc. Sometimes we will have him read, help out, find something to do. Or I will say I always have chores to do!
It is a struggle.
You could always make a chart and have them earn time on electronics. Chores, homework done, reading, outside play, etc. whatever you want them to do. Have them complete items to earn time.