Leto II Atreides is a fictional character from the Dune universe created by Frank Herbert. Born at the end of Dune Messiah, Leto is a central character in Children of Dune and is the title character of God Emperor of Dune. From Wikipedia
The new casting underscores a significant time jump in Denis Villeneuve’s final Dune instalment, paving the way for Jason Momoa’s return as a ghola.