Great modern example since all three of their records rule and they just broke up and don’t seem likely to reunite any time soon.
Their friends Black Country New Road also currently have 3 (if you count the live album which is all new material so i think that’s a valid reason to count it), though they’re still truckin along and will probably drop another album soon.

adebisi shank - one of the rare “modern” bands (they broke up 10 years ago if that counts as modern anymore) that George covered and liked, I never would have heard for them if not for him but they’re pretty good.
Portishead - I’ve actually never spent too much time listening to them, I owe them deeper listens one of these days, but they’re one of the more obvious ones.
Avalanches - People seemed to like them more when they were a one-album band but IMO their 2nd and 3rd records are both pretty good. It’s likely that a fourth album will appear eventually and disqualify them from the list.
Vashti Bunyan - She’s still alive but probably a safe bet she wont manage a fourth record.
Liquid Tension Experiment - ok this is only a good band if you like Dream Theater prog noodling, but hey i’m not gonna pretend I dont.

I almost said daft punk, but then remembered that Human After All existed (boy, did that album get swept under the rug).

this is a bit tricky not because there arent many worthy artists, but because it’s much harder to come up with 3 album bands than it is 2 or 1 album bands. There are probably many other good current bands with three albums that are likely to continue on releasing albums.