Luffy has shown tremendous growth in One Piece as of late, and the Wano arc was the most significant one for him in this regard. Here, Luffy learned to tap into some of the most significant forms of this power. Not only did Luffy learn how to utilize the power of Ryuo, but, in the battle against Kaido, he went on to tap into the power of Supreme King Haki as well. To take things one step further, he also went on to awaken his Devil Fruit, and this gave him access to the true power of the Hito Hito no Mi, Model: Nika, or in other words, what Luffy calls Gear 5.