When Does Luffy Go Gear 4 [patched] Link

Luffy adapts the core mechanics of Gear 4 into specialized variations to counter the specific combat styles of later adversaries. 1. Boundman (Bounceman)

After Doflamingo trapped the kingdom of Dressrosa in his "Birdcage" and began a massacre, Luffy realized his standard Gear 2 and Gear 3 attacks were not strong enough to defeat the Warlord. Needing a power that combined massive strength with the speed and elasticity of rubber, he unveiled his new technique.

: In the Wano Arc and beyond, Luffy has mastered the form enough to engage and disengage it more freely, significantly extending its duration. Expert discussions on Reddit highlight that Luffy's control over Gear 4 now allows for more "flexible" attacks, focusing Haki on specific parts of his body as needed. One Piece: All of Luffy's Gears, Explained - Crunchyroll