What do you want to know?

You should look up counterfactual regret (CFR) minimization, it has been the technique that underlies all the expert poker bots.

Then, if you are interested in hold'em variants, look up DeepStack, Libratus, Pluribus, ReBeL, and Player of Games.

All of the competitive bots on the hold'em variants use some form of specialized search (based on CFR or Monte Carlo CFR) over the public belief state tree.

The card draw variants are mostly untouched because the public tree methods are not as easily applicable.

Anyway feel free to dm me if you want to know more.