I’ve used “not WT 2.3” and “WT 2.4” Maxxis DHRII tyres on the same 30mm internal rims and WT is defo a bit more suitable, the narrower tyres just square off a bit.
I have also used Specialized 2.6 and 2.3 (bigger than maxxis 2.3) on the same 30mm internal rims and both work well. Aaaaaaand I’ve used a narrower (25mm I think) rim with the same specialized 2.3 and that’s fine too.
The only issue I have had with running not-WT 2.3 maxxis on 30mm rims was the old Minion SS which was semi slick in the middle of the tread, so you’d end up with the should knobs taller than the centre due to the squaring off.
TLDR: 30-35mm internal rims will be fine with anything from 2.3 to 2.6 in my experience.