100BB effective pre
relevant read is CO tagged as passive player post, generally betting more with his big hands and not bluffing much on River

Hero (MP) AQ 2.25BB, CO RAISE 6.75BB, rest fold

Flop (15BB): 3 A 2

Hero check, CO bet 5BB, call

-is this the proper cbet sizing? Most people in my game are raising me to 10 or 10.5BB even in position. His sizing felt a little weak.
-on the flop, his cbet seemed standard 33% but certainly still thinking about him having AK here, I didn't raise flop. Should I have a raise here with AQs?

Turn (25BB): 8

Hero check, CO bet 18.75BB, Hero call

-bigger sizing makes me feel bad but still in check call mode

River (62.5BB): A

Hero check, CO bet 69.5BB and is All-in, Hero?

-it's less likely he has an ace, the spades missed, no more straight draws came in?

I call thinking there are a lot of missed draws, and maybe he will have AKo,

Villain (CO) shows 8 8

Knowing that he is three betting me this wide might change future decisions like not 4b, and not to raise flop?

do you mean proper 3bet sizing? it's fine. 2.25>10 is good OOP, but quite large IP.

if your read is correct, kind've a gross spot on the river honestly. solid opponents don't follow through here for overbets (even though it is slight) terribly often, and i'm not sure if AJ is even in there for the larger bet. AQ will be and it's usually not great to fold a hand that could be splitting with his valuebets, esp when those splits happen at such a high frequency. if value is all AQo+ and 1.5ish combos of 88, we're lookin at 3 combos of bluffs to call. not that many obv, but i think there are a good chunk of players with 0 bluffs on this river. so... usually call, but if he snapshoves and is solid you can probably fold. if his 3bet range is tight and top-heavy it can even become a very clear fold (fewer AQ combos in there, less JTss to bluff with)

i would warn you though, and i don't mean this in a bad way, but you are giving me the impression you're more in the beginning stages of your career, and beginners don't tend to be great at player assessment, and moreover overestimate their ability to do it (this is true to some degree with players at nearly all levels). a ton of things happen at the poker table and some of it means very little, some of it means something, and some of it means a lot. most beginners just don't know how to accurately evaluate all that stuff. just comes with experience and observation. rando advice there for ya.

88 is a fine 3bet here btw

I'd mix calls and 4bets pre. AP the hand is completely standard though, you dont want to have a raising range OTF since you are doing quite poorly on that flop compared to his range. OTR its one of the best hands you can have on this runout and you unblock his spade barrels.

thanks for the feedback and tips on sizings

If this guy is passive post, he's not going to be betting a bdfd otf. As for villain's range, hero is only behind 2 hands here (that are 3bets pre), AA and AK. Hero is ahead of everything else (KK, QQ, JJ, TT, etc.). Neither should have A3 or A2 in their ranges. And believe it or not, AQs actually is 62% against CO 3bet range otf....

exact opposite

lol
min bet flop, pot bet turn, all-in river - classic fish move - insta fold river

Turn - insta putting him on Ax 2p, 88,45 in that order (i doubt he 3bet 45 )

if it is pokerstars he will have A8 by the river!

This villain took the most standard reg line possible that most of the people reading here would take. What in the world are you talking about "classic fish move"? 1/3 pot on a dry flop in a 3bet pot IS standard sizing, it's definitely not a "min bet flop". Regs are going to absolutely own you in 3bet pots if you falsely believe standard lines are bad and they are somehow "fish" for taking them.

:/ yea dude pretty sure 1/3 pot sized bet has been standard since pio came out

stupid af