Is there any room for improvement?
IMO,turn maybe is a relatively marginal fold.
if I call turn,I think maybe the 3bettor will jam more hands.
GGPoker, Hold'em No Limit - $0.50/$1.00 - 6 players
Replay this hand on Upswing Poker

UTG (Hero): $116.25 (116 bb)
MP: $156.35 (156 bb)
CO: $516.46 (516 bb)
BU: $89.34 (89 bb)
SB: $92.20 (92 bb)
BB: $109.39 (109 bb)

Pre-Flop: ($1.50) Hero is UTG with J♠ J♣
Hero raises to $2.10, 2 players fold, BTN 3-bets to $9, 2 players fold, Hero calls $6.90

Flop: ($19.50) K♦ K♣ 2♥ (2 players)
Hero checks, BTN bets $6, Hero calls $6

Turn: ($31.50) 9♣ (2 players)
Hero checks, BTN bets $17, Hero calls $17

River: ($65.50) 2♦ (2 players)
Hero checks, BTN bets $57.34 (all-in), UTG (Hero) folds

Total pot: $65.50 (Rake: $4.50)
BU wins $61

Gross spot. I don't think you can do anything differently besides the turn. I would say it's all about opponent tendencies. Against aggressive players they will oftentimes be three barreling with nothing here and you will have to pay off and be willing to go broke sometimes. If it's a tight player, there is almost no way you are ahead here. If he has TT he will likely slow down in position after you called a flop bet on a K high board and another K comes. The 9 is a particularly bad card too since 99 is one of the hands he could conceivably have. You are really only beating a pure bluff since 88 or lower would be unlikely to barrel turn.

That said, folding here can open you up to being exploited so make sure you are only doing it against straightforward players.

We have so few kings - a few AK, some KQs-KTs whereas he has all the AK and a lot of KQo

People on here say triple barrels are overbluffed. His stack is broken, so he may be a fish. I think we have to call down.

Even if he is a fish, I am having a hard time coming up with bluffs he could have. The flop contains no draws. Would a fish really triple barrel with AQ here? We block all the bluff combos containing a jack. Does he have TT and is trying to get value from...what, T9, which he blocks? A9? That's two potential hands and the ones that beat us are AA, AK, KK, KQ, KT, and QQ. We have to be right 32%...doesn't seem like we are getting the odds we need.

It would help to have stats to make this decision.

Exploit folding turn seems ok in this specific scenario (shortie + oop + dry board + flush blocker + milky sizings)

We never have AA/KK/QQ/AK, and we 4-bet KQs at some frequency. Feels like we're at the tippy top of the world's poorest range. Spin RNG, but against this villain I call.

What's up with that large 3bet BTN vs UTG?
Insane!

I would - as an UTG nit - just fold this pre against this raise size.

You young guys are crazy.

You certainly own us boomers.

Is there any room for improvement?

Answer: Fold pre.

that's the old meta, when you OR 3bb and they 3bet 9bb lol good times, nowadays you open at like 2,2bb and 3bet to 11bb, its a standard 3bet