I’m no parent but if I was I wouldn’t allow children onto the internet until they were old enough to join the army !
However, if I were you, the optimal solution would be to create a vlan for children, then you can apply your rules / blockers etc to that vlan while adults can use their common sense on another vlan !
If you had pfsense then it would be easy to block all the crap network-wide with pfblocker, which is what I do.
Alternatively, with the kit you have you might want to investigate pi-hole, it’s been a long time since I used it, there might be lists that you can add to it to block other crap in-addition to ads which was its original purpose.
BTW pfsense also has a schedule feature so you could in principle stop a vlan from accessing the internet based on time.
Obviously if your children are smart they could circumvent your controls by setting up their own VPN.
For sure segment your network otherwise your controls will affect all users.
Given all the crap on the internet I’d be aiming for advanced controls at home as a parent !!