DNS ad blocking on iOS has been fine a few years at least. I've been using NextDNS on mine since 2020. I actually shocked some family members at how easy it was to setup on theirs, to the point where they felt weird not seeing the ads plastered everywhere. One actually wanted them back. Stockholm Syndrome, I guess.

You can use either their app, which toggles a network profile for the DNS, or install a MDM profile from their site, which is a more persistent option. I prefer the app as you can toggle it off if something isn't working and you want to confirm whther the DNS is the culprit.