A lesson can be learned from timezones in #Unix.
At (almost) first there was the simplistic implementation of the TZ environment variable having something like GMT0BST1 ; then extended to things like GMT0BST1,M3.5.0/01:00:00,M10.5.0/01:00:00 . This was 'good enough' for people who didn't care about time from a few years ago; and who didn't live in a place with multiple timezone jurisdictions; and who didn't travel widely. It got ossified into the Single Unix Specification.
https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/V1_chap08.html#tag_08_03
Then came the Olson tz database which encoded the complexities of odd laws and complex histories in loads of differing jurisdictions around the planet.
Of course, the laws on #AgeVerification are already following the latter model.
The simple dæmon + account database age field system that I predicted on 2026-03-01 is the simplistic implementation.
An Olson-level implementation will need to know current location, business/work/school/personal use, & accountholder's parents.