For that can't you use Private DNS / Encrypted DNS pointing to a PiHole or nextdns etc? My memory is that iOS you have to change the DNS settings for each network which is sort of a headache, but one-time at least.
on macos, i used to use hands off! from one periodic (and before that, metakine), but they've since disappeared. i now use lulu with pf firewall via murus lite as a backup, but may switch to little snitch again (used to have a license but was unable to upgrade it so switched to hands off! via a promo) for the better UX.