Villain has ~300, 30s-40s white guy reg, have seen him be fairly aggressive but have never seen him have a bluff in any large pots before, and actually in particular have seen him have the nuts in those scenarios. but he hasn't played any big pots at this table yet.

Hero covers, table transferred about an hour ago with a large stack, currently with a fairly tight aggressive image but not crazy, have the impression that some of the players are afraid of me for having a big stack, folding to a lot of my pfrs or cbets

Hero holds K K on the button

Villain opens from utg to 8, 1 caller, folds to Hero who 3-bets to 30. folds back to Villain who calls, other player folds

(63) flop Q 9 7

Villain checks, Hero c-bet 40, Villain puts out a checkraise to 100. Hero calls

(263) turn 6

Villain open jams for ~170. Hero? What are we beating that he would open jam?

Maybe AQ with the ace of hearts? Not much.

I will usually check back the flop with such a draw heavy board, and play some turn. If u check back this on flop, villain usually put u on AK or JTs and then if he lead out on turn, call it down unless he plays trickily on river.

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It's fine up to the flop check/raise. That is the point where you should have asked what calls the 3 bet preflop and check/raises flop that your beating? AA still beats you, QQ now beats you, AK is bluffing except AhKh, AQ is being very optimistic on the flop. Lower sets are possible but the only likely draw is AhKh unless villain is very loose and aggressive. Plus, villain's flop raise is not big and if you call villain will have much less then a pot sized bet left. Without any other information giving up on the flop is best.

You have one pair/no draw on the turn facing a jam from a guy you describe "have never seen him have a bluff in any large pots before"
There are a lot of hands that beat you and only a small group that your are ahead of (AQ,KQ,QJ) so IMO fold is appropriate