I don't get why people want 5 acts in the first place. Like, what do you hope you'll get from it?
I still believe that's it's likely that Oda's initial plan for Wano was a 5 act structure, but like his editors said his pacing has been crazy during Act 1-2 which might indicate that Oda sacrificed plot points to shorten the arc.
It may be possible that the entire war will end in Act 3 and then we'll get a short Act 4