CO is an aggro reg
Stacks:
UTG - UTG ($38,41)
MP - Hero ($26,21)
CO - CO ($25,00)
BTN - BTN ($27,93)
SB - SB ($23,88)
BB - BB ($27,39)

Preflop: ($0,35, 6 players) Hero is MP with Qc Qd
1 fold, Hero raises to $0,75, CO raises to $2,25, BTN calls $2,25, 2 folds, Hero calls $1,50

Flop: 6d Kd Ks ($7,10, 3 players - Hero: $23,96, CO: $22,75, BTN: $25,68)
Hero checks, CO bets $2,75, 1 fold, Hero calls $2,75

Turn: Kh ($12,60, 2 players - Hero: $21,21, CO: $20,00)
Hero checks, CO bets $6,75, Hero calls $6,75
maybe I should shove, but i cannot have any bluffs by raising

River: Kc ($26,10, 2 players - Hero: $14,46, CO: $13,25)
Hero checks, CO bets $13,25 (all-in),
Hero ???

I folded here, but maybe I could hero call Vilain, his range seems bluffy balanced : there is little AK, i block AQ and it's ambitious to 3 barrel his Ax's on this board.
Sorry for my english guys, thanks !

Likely just go ahead and 4bet pre and gii with the added dead money from btn in the pot.

4bet pre especially considering you say co is an aggro reg + button cold call

While yes he can't have AK, you block AQ and there are few AX hands he should bet the turn with he can still just have Aces, I guess if he turns jacks into a bluff here folding is bad but why would he you rarely have an ace or a queen on the river especially considering you should 4bet queens pre so he has a lot of showdown value with a hand like jacks.

I 4-bet QQ HJ vs. CO. Considering this is multiway and you've got a guy who just took a 3-bet to the face and whose range we are basically always ahead of, I'm even more inclined to 4-bet. Let's just get it in.

Postflop as played is... bizarre. If we're folding QQ we're also probably folding JJ-77, and I'm not sure how many of our Axdd combos actually call turn. Once the board removes all the Kx's from our range, QQ seems really high up in our range from a MDF perspective.

Regardless, calling feels wrong because villain has the most ridiculous range advantage I think I've ever seen in a hand -- villain can have all the AA combos while we can't have any, and I think villain is more likely to bet Axdd OTT than we are to call with them -- which I guess is why we're debating whether we can call with anything that's not the nuts.

I don't know what I'm doing OTR. Probably sigh calling, but man does it feel wrong.