Haki is the mysterious power of spiritual energy in One Piece. As an example, Busoshoku Haki can allow users to convert spiritual energy into armor.
Luffy can generate fire in a red hawk attack, it may be a type of Haki that allows users to generate fire from spiritual energy. Similarly, Sanji, Zoro, and Kin'emon can generate fire. Kaido and Yamato can generate lightning using Haki.