Hi, pretty standard to me, never mind if you get called by a better hand

What about the preflop 3b with 88?

Not sure both of these players can be that strong, facing a lead by the SB, CO could be calling with simply a pair or a draw

Shoving is your best option, you can't just flat call on this board against 2 players.

Agreed. I don't see any other play besides shoving here.

Your shove would be less than a pot-sized raise at this point, and the board is just way too draw-heavy to think about just calling here.

And for all of those same reasons, that makes it unlikely that the CO is calling here to trap with a monster hand. With the stack depth, and two other players, he too would be incentivized to raise on this flop, even with his monsters.

In a 3-way, 3-Bet pot, with this draw-heavy of a flop, we should simply be getting all-in with 110 bbs to start the hand, especially if it is made this easy with a lead and flat in front of us.

Shoving and calling doesn't make much of a difference, everyone is committed anyway after we call. Hands that can be scared OOT are 2pair or overpair or something. CO doesn't have those and SB can't fold anything anymore. For the same reason I wouldn't be reading too much into CO's play. He is effectively all in after his call might be trapping with a nuts might be buying himself better odds for his draw.

I would fold tho.

I'm not sure I like the preflop 3 bet BTN vs CO when the CO is playing 19/11. I know that he hasn't 4 bet yet over your sample but he has a pretty tight range here. As played, I don't think that there's much to do here other than jam on the flop.