Welcome here! See Large ASA prints warping which has info not necessarily limited to ASA.
You didn’t mention any settings you’re using. Have you tried a raft? How do you let things cool off, etc.
Something to consider is carbon fiber or glass fiber infused filament. Not for the strength but for the reduced warping. I know it costs more…
I’ve been contemplating a glass plate, but I think in the end one has to figure out how to relieve the stresses during printing otherwise they will do that over time afterwards somehow.