I believe luffy will develop this technique on Elbaf in order to fight de giant antagonist there.
Didnt luffy already become giant oh wait it was that stupid filler
Giants can use haki since Saul and John amongst other giant vice admirals are all haki users
Almost all vice admirals are haki-users
It's stated All vice admirals use some form of haki
Considering that Harjudin got one shotted by Luffy it wouldn't seem like he would need to. I don't remember if this is just me making this up or if it was said but isn't harjudin one of the stronger giants?
Well, he is a captain of his pirate group and has an ambition of becoming king of giants, so I dont think this ambition of his is not based on some strength qualities.
Have some more imagination.
Personally I feel like the Straw Hats will get the giant serum that Caesar was working on, and they'll keep it until Elbaf.
(It's a loose thread from the Totto Land arc. I know the serum would have to be temporary, but it's possible).
Which giant serum?
What do you think?