Caesar Clown was captured by the Straw Hat Pirates and eventually handed over to the Marines.
After his defeat at the hands of Monkey D. Luffy and his subsequent capture by the Straw Hat Pirates, Caesar Clown found himself in a precarious situation. Initially, he was used as a bargaining chip during the Dressrosa Arc, where the Straw Hats formed an alliance with Trafalgar Law with the aim of taking down the Emperor Kaido, for whom Caesar was producing artificial Devil Fruits known as SMILEs.
Throughout the events that unfolded, Caesar’s knowledge of chemical weapons and his scientific expertise made him a valuable asset and a dangerous individual. His past actions, including the horrific experimentation on children and the development of weapons of mass destruction, made him a target for various parties, including his former employer, Doflamingo.
After the defeat of Doflamingo and the chaos that ensued on Dressrosa, Caesar’s fate became uncertain. He was taken along with the Straw Hats to Whole Cake Island, where he was involved in the plan to rescue Sanji and sabotage Big Mom’s operations. Despite his unwillingness, Caesar played a crucial role in the Straw Hats’ escape from Big Mom’s territory.
Following the events of Whole Cake Island, Caesar’s whereabouts became unknown. It is implied that he managed to escape and go into hiding, as he is wanted by many powerful figures in the world, including the Marines, the World Government, and various pirates. His current status and activities remain a mystery, leaving his fate open to speculation among fans of the series.