FOSSEON

I am very curious what other's input will be, as this is an important question!

I don't know how old they are, but kids these days are usually pretty tech savvy so it will be hard. You can get an app locker app to password protect certain apps like app stores and web browsers, but even then if they find out they can uninstall the app locker to disable the protections, then you're back to square one. Brave Browser has content filtering which you can enable to block malicious websites, foreign sites, p*rn sites, and specific domains you choose to block. Same thing though, this can be disabled if they know where to look. An advanced option would be to set up a proxy on another computer that the phone links to, and that computer acts as a firewall, so they'd have to have access to that computer to unblock certain things. On another note, as someone who grew up with protective parents, it only creates curiosity. My personal opinion is to either not give them a phone or teach them good digital habits based on trust. The ladder really resonates with a child in a positive way :)