"In Revelation 19:16 Jesus is given the full title “KING OF KINGS AND LORD OF LORDS” (Revelation 17:14 switches it: “Lord of lords and King of kings”). The title indicates someone who has the power to exercise absolute dominion over all His realm. In the case of the Lord Jesus, the realm is all of creation. In John’s vision, Jesus is returning to judge the world and establish His earthly kingdom, as He predicted in Mark 13:26."
See: What does it mean that Jesus is King of kings and Lord of lords? (GotQuestions)