The location of the Last City in Maze Runner: The Death Cure is confirmed by a few small details in the film. The movie is the final installment of the Maze Runner franchise, which focuses on Thomas (Dylan O'Brien) and his friends as they continue to battle WCKD, the evil organization that trapped them in mazes for their experiments. They learn in the second film they were chosen due to their being immune to the Flare, a zombie-like plague that has destroyed the world.
https://screenrant.com/maze-runner-death-cure-last-city-location/