There two ways to combat his aggressive 3bets. We can 4bet pre like 2.25X and see how he adjusts, like, does he flat wide or does he come over the top? A guy who 3bets this much, I'm actually pretty curious to see how he adjusts.

Flatting pre is not bad either because he is likely dominated, a ton of weak Ax/Axs in his range. I think this line is actually more punishing should we hit the right board, and this one seems to be one of them, may be until river. Yeah, KQ is a problem. I can't fold river though because I think we kind of have to stick to our line which is to play the hand passively on the board that hits his perceived range but hits ours harder in reality. It's probably like a break even call but we also get to see his hand which I think is helpful in future, well, hopefully within this session.

I wouldn't do it with this exact hand because you are possibly too high up in your range but I think a check-jam bluff could be  +EV here with some of your Ax combos. It's been a while since I played these stakes at 6max but when Villain caps his range on the turn he shouldn't have too much of a river betting range so you need only fear AK of which he will barrel a % of the time anyways. You block Aces-Up and he would be barreling most of the combos that would be comfortable calling an AI check-raise such as sets. Like you said, a weird KQ/KK is a possibility but KQ could/should fold to check-raise.