Pretty much what Zenzu said
There's no world where Koby (realistically) catches up to Luffy without bullshit even if Oda included a million different training montages
Almost every notable and strong character in One Piece started fighting/training from an incredibly young age
Luffy, Zoro, Sanji, Law, Jinbei, Yamato, Ace, Sabo, Garp, Kaido, Shanks, Blackbeard, Whitebeard, Big Mom, etc
Just about every exception took
decades to hit their prime like Roger, Rayleigh, or the Admirals
Koby at
16 with 0 battle experience shouldn't be able to catch up to Luffy till way later in his life
