And after 2 years, all these animals are afraid of Luffy. So, do you think that he was able to do all that with just gear fourth and base form of Haki? It all indicates that Luffy has one more power that he hasn’t revealed yet. And in my opinion, the form that Luffy hasn’t revealed will be the gear 5. Now this does raise a lot of questions. Why would Luffy not have shown us Gear 5th until now? What’s the point of hiding it?
Another question may arise that why didn’t Luffy use this new gear against Doflamingo and Katakuri if he had it in his arsenal. The answer to this is that gear 5 takes a lot of toll on his body and is his last power. He didn’t use it against Doflamingo or Katakuri because he didn’t need to use it. As it is his last power, he would use it as his last resort but he didn’t need to go to that last resort. To understand Luffy’s gear 5 we need to look first at his previous gears, these are Gear 2nd, which he invented against CP9, Gear 3rd the same and of course, Gear 4th which he got during the Timeskip.