Sorry, Superman, the DC Extended Universe's "real" Doomsday is still out there, somewhere.
Responding to a question about whether the virtually unstoppable creature was actually defeated in Batman v Superman: Dawn of Justice, director Zack Snyder responded on Vero, "yes the real doomsday is out there still."
In the 2016 film, Doomsday was created by Jesse Eisenberg's Lex Luthor using his own blood, the body of General Zod and Genesis Chamber technology from a crashed Kryptonian scout ship. Presumably, then, the "real" Doomsday would be the genetically engineered monster from Kryptonian history.
Luthor's creation battled Superman, Batman and Wonder Woman before ultimately being destroyed by the Man of Steel in an act that also killed the hero. Of course, Superman was resurrected last year in Justice League.
Snyder's revelation follows his suggestion in April that the Robin costume displayed in the Batcave in Batman v Superman didn't belong to Jason Todd, as was widely believed, but rather the Dark Knight's original sidekick, Dick Grayson. It's difficult to say whether the filmmaker intended to introduce the "real" Doomsday sometime down the road, but considering Snyder is no longer the caretaker of the DCEU, it seems unlikely that creature will emerge to face Superman again.