Playing 2/5 NLH and get KK on the button. A raise to 20 in front of me and one call I elect to 3B to 65 (not sure about this sizing maybe a little small) both players call the raise and we go to a flop of 10s9s3d both players check the flop and I bet 85 (I believe I should of sized up with this bet) the first player then decides to shove over me for ~500 effective and other guy folds. I am not thrilled with the situation but dont see a way I can fold and although it seems TT is a very likely holding I feel like QQ (although possible queens can 4B pre) and JJ as well as flush and straight draws can play this way. I make the call and the bored comes runner runner spade to which I have the Ks and take down the pot he never showed his hand curious to what the correct thing is to do in this spot.

3b bigger. Never folding post.

Hi

I would 3bet to 80min pre
Imo Flop is wp

Thank you makes sense to not price in those hands.

Thanks for answer.

Pre is fine. You made a pot sized three bet, which is already on the large size, but a completely reasonable approach. It is a delicate balance because you don't want to lose your opponent by charging too much, but you do want to charge as much as you think they will call.

On this flop with an SPR of 2, you have to go with the hand, especially after you bet.

Your flop sizing is fine too.

This is not a pot-sized 3bet.

This 3bet is not a standard or reasonable size.

The 3b should be somewhere in the $80-100 range.

Welcome to the world of 'it depends' .. There are plenty of factors to consider, including stack sizes, player types and your percieved image on the Button .. as well as the tendency for the blinds to come along.
You want to 3-bet to a size that hopefully gets you no more than 1-2 callers.

The Flop has the same considerations. Your bet size here has a hint of caution to it and induced action, which is fine if we know we are going the distance. You can also go bigger since this board is wet, which may imply both protection or a large draw on your part.

I think you should find that live play 'requires' more variation due to table and Player dynamics. GL

How comes he never showed his hand? You said he shoved over you and you called. So he has to show his hand.

Never fold to this bet. Probably some OESD with FD or as you said a set

Got antsy and showed mine first he mucked

Indeed, making it potsized is a reasonable approach. But that also requires the knowledge of calculating potsize. $65 isn’t even 3/4 of a potsized raise.

Why the heck is this titled overpair vs. set?

If you make it $80 pre then there is $180 in the pot with $420 to play, SPR = 2.3. This is fine for stacking off as he can never set mine against you profitably, or otherwise.

As played, way too many draws and combo draws that he can have to ever fold. Against a few players you can make an exploitable fold, but never in a GTO sense and not against the general population.

The title was more of a theory like what am I supposed to do with an overpair vs set on the flop. Do I just stack off or?? Guess it depends...

Not in a cash game (in most rooms).

If you were a superuser (or villain showed you his cards), so you knew he had a set for sure, then stacking off with an overpair would be ridiculous, unless the shove size was tiny, as you'd only have about 10% equity on the flop, basically needing to hit a 2-outer.
You should only be calling off your stack if the pot lays the right odds to do so. You could call a pot-sized jam if you had 33.3% equity, for example, but an overpair is drawing very thin vs a set.

Size up the preflop raise. 3x is fine in position against one caller, but with a second caller, you need to go bigger. Like 4-5x.

Cbetting $85 into a $200 pot on the flop, multiway, on a very wet board, seems bad. Again I'd size up.

After the check-raise you need to call $415 to win a total pot of ~$1200, so you need to win at least 33% of the time to make this call. It's a pretty close spot, to be honest. I could see some straight/flush draws doing this, but this raise is definitely value heavy.

You won the hand with a runner-runner flush draw so you must have had the Ks blocker. To me, having the Ks makes calling even worse because you block many of the flush draws your opponent could be doing this with.

It's a really close spot. I think against a competent opponent I'm cry-calling, and against a value-heavy (read: average live player) opponent that clearly isn't bluffing enough, it's an easy fold. I just don't see you winning this more than 33%.