I want to be very clear on something and this is not from me- this is from Nasir Al Hanbali, I heard him discuss this (I know him in real life and I actually knew him before I found out he had the YouTube channel... he really is a talib al ilm in real life and he is seriously knowledgeable and very well respected by Muslims who know him in real life)....
if you have a child, young child, or say they are 14.... 5, 8, 9, 13, 14.... DO NOT GIVE THEM A CELL PHONE. again I heard this from Nasir, this is not from me.... hoooowever.... if you absolutely need to give them a phone and there is a need for them to have one.... give them one that doesn't connect to the internet. they can call you, text you, etc.- but no access to the internet. one that's not a smart phone.
also... and I think this is also from Nasir- if you have kids, and you need to let them use the internet, say for a homework assignment.... no laptop, no letting them take the laptop in their room.... have them use a desktop... say in like the living room.... they use it in your presence and where you can see what is on the screen.
of course, if you have kids what you do is ultimately up to you, all this is just advice but I really urge people to be careful when it comes to protecting their kids from all the garbage that's out there.