UTG is 44/26/1.8
CO is a TAG 25/18/2.3

pf: Hero is BB A 9
UTG raises, CO calls, 2 folds, hero calls

flop: 9 3 6
hero checks, UTG bets, CO raises, hero...

Tricky hand where I think your opponents have a lot to do with your decision. UTG looks like a loose aggressive monkey and CO has standard TAG #'s. If TAG is thinking and knows UTG is a loose monkey then he could be raising with a wide range of hands here including a weaker 9 or many weaker pairs.

What kind of hand does this player coldcall a raise with here? I think hands like 89s 9/Ts or pairs smaller than 9. What kind of hands does a loose monkey cbet the flop with here? I think everyhand that he raises preflop with.

Overall I think your equity is very good and you should 3bet trying to force out UTG if he has a hand like KQ or KJ.

3 bets? Tag is going to raise a ton here to get you out and isolate the bad player. What hands does a TAG call 2 cold with that have us in bad shape? Duck and cover a club turn though

Easy 3-bet. Only hands TAG can have, that you're behind to are 33 and 66. Most likely is T9s, 98s or a flushdraw.

the other aspect is that there are a lot of overcard hands the other guy can have that you want out now.

so

you are actually ahead of the raiser's range, and
you want several hands in the bettor's range out of the pot

fold preflop

3-bet the flop, but preflop is a fold.