A3s third bar in 3b pot OOP on board with many draws completed?

Which means, that if we are bluffing, we want to make it bigger, to make opponent fold?

Well not really. If villain is going to fold he will fold to a smaller cbet OTF. 1/2 should be perfect, bigger bet is not needed.
And there is one more thing: we bluffed pre flop which is fine, but I'm not sure we should continue bluffing postflop because now villains range is quite strong and we have only a backdoor. Imo this would be a good spot to use delayed cbet or just check call.

You should be making same size as a bluff and for value.

What I´m afraid of is, aren´t we making cbet easy to call, when it´s just 1/2 of the pot? (at micro/low stakes)

what I understood from Lemon is that vs 1/2 its easier to fold for villain because he often does not get odds and he does not make mistake.

But vs 1/3 it becomes tougher because he does get closer odds to call with weak hands like A high. And if he folds too often, we bluff him cheaply. If he calls, we can 2nd barrel to make his Ax and other marginal hands fold.

I was talking in general.

Which means, that if we are bluffing, we want to make it bigger, to make opponent fold?

Usually 1/2 should be enough. But bigger size should increase fold equity I guess if player is thinking. I guess it will not make more top pairs fold, but if player calls marginal hands like A high vs 1/2 bet, then vs 2/3 he could fold I think.

Plus when deep, we have to cbet bigger because of implied odds he has.

As nitrol said we should also have value hands with same size, but I think this matter only vs smarter players or ones who you play more hands with. For example in zoom I believe many do not simply care about exploiting one oponent in micros. So I believe it is possible to exploit them by not balancing.