Conqueror's Haki, also known as the Haki of the Supreme King, is the rarest form of Haki that only a few people in the world of One Piece are born with. Unlike the other two Haki types, Conqueror's Haki can't be learned through training and is only possessed by those who are born with the spirit of a king.
Source：https://www.cbr.com/one-piece-conquerors-haki-users-ranked/
