You don't always have to 3-bet your AAxx hands, specially when you are OOP. Cbetting from IP is so much easier like situation you described.
I don't know the stakes you're playing but with my experience from micros I can say there is not much folding against 3-bets, so villains can have literally anything.
In T23ss board you can try to figure out what is villains 3-bet calling range from CO. Would he open from CO with T2xx, T3xx or 32xx combos and call 3-bet? And what are your side cards, are they blocking anything?

Your c-bet sizing (unless the SPR is extremely low) should be sized according to how draw-heavy the board is and how well it connects with your range.

To start off, you can bet small like half pot and then look what villain is doing. You have to decide here from time to time, but be aware, it is hard to hit 2pair or set so be prepared to stack off frequently on such dry textures especially against weak or aggressive villains.