If you play game theory optimal (GTO) then you by definition can not be exploited. For poker a GTO strategy is extremely complex where each decision you make depends on the exact situation and includes varying your decisions over time. Like bluff raising 60% of the time and folding 40% of the time you’re in some very specific situation. It’s basically putting your opponent into a situation that they can’t make a profitable decision in the long term.

It’s not really practically possible to do. But if two people did they would have 0 expected value over time against each other. If one player slightly differed from game theory optimal strategy that would give the other one positive expected value. There is no way they can change from GTO strategy to exploit you.

However, this isn’t necessarily the most profitable way to play against real people. When your opponents aren’t playing GTO, there will be some non-GTO strategy that exploits them most effectively. Like if they call too much then you should raise for value more often than against a GTO opponent and bluff less.