Pirate Loyalties: Kuro of a Hundred Plans (Patreon)

This one uses a sort of 'tg story sin' of 'hypnosis somehow causes physical change'. Given Luffy's power you can sort of justify it as his body stretching to match his mind but the real reason is just in these early arcs there's not a ton to work with for tf triggers especially if there's no devil fruits at play so we just went with Hypnosis as the most interesting element available.