[thepete2]

I don't know if this is a thing, but chess players might also steer the game in a direction/position which their opponent hasn't studied much, but they have. There's a "social" side to this seemingly "mathematical" game, no?

[thom]

Fabiano Caruana (previous World Championship challenger) has said that he’s happy to find lines where the machines have you slightly behind, purely because they’re less like to have been studied in detail by your opponent. Even with perfect recall of the first 20/30 moves in various lines, players are still going to steer away from some lines based on their and their opponent’s strengths (tough against super GMs with few weaknesses though). So you’re definitely right, I think there’s a lot of game theory here, albeit much of it settled by your team ahead of the actual match.

[JulianWasTaken]

This is more so in the opening (the beginning of the game, and separately where engines tend to be a bit less informative) but yes it is definitely part of the chess metagame, and you'll often see commentators talk about whether someone is "still in prep" or has gotten out of it. It often can lead to time advantages if one gets an opponent out of prep.