I’ve tested Canopy Blocker on my kids’ devices and it does block a lot at the DNS level, but savvy tweens can sometimes switch to mobile data or a different DNS and bypass it. On iOS I actually prefer built-in Screen Time (Settings > Screen Time > Content & Privacy Restrictions > Web Content > Limit Adult Websites) plus setting a Screen Time passcode—Apple’s solution is rock-solid, always stays in place, and you don’t have to worry about DNS leaks. If you want extra logs or alerts, Bark and Qustodio both have great iOS support.
Android’s parental controls tend to be more fragmented and can feel less reliable across OS versions. On iPhone you get consistent updates, strong privacy safeguards, and zero chance of a back-door escape.