User blog comment:Kaido King of the Beasts/Chapter 904: The Revolution Will Not Be on the Loudspeaker/@comment-25654036-20180512111738/@comment-25501246-20180512163829

His introduction has him as much bigger. It's just a drawing inconsistency.

Plus, if we have the citizens, pirates and Betty calling him a Giant, then we have no choice but write as such. They're the only source we have.