NL 50 SH should i barrel here ?

I think K9o is quite weak from CO, especially with someone with reasonable 3bet% in the blinds. I would just fold it preflop.

Since you opened it, why did you cbet? He doesn't like folding to cbets and you have next to no equity. This problem starts from preflop though because your hand rarely flops good equity to barrel against people that don't like folding easily.

I think it's a very bad spot to barrel because he will often have Ax, he can slowplay nut type hands as well since board is dry and you have 0% equity. I would not cbet at all, I think turn barrel is even worse and I think betting the river is complete spew. Now he is not folding any pair given his tendency to not believe bets.

Furthermore, you bet sizing on the turn is quite small compared to when you have a value hand imo. I would often read it as weakness.