Warner Bros. doesn't call its own annual CinemaCon presentation "The Big Picture" for nothing. Perhaps feeling the heat from box office behemoth Disney, the studio brought out the big guns this year, from DC movies like Joker, Birds of Prey and Wonder Woman 1984 to Godzilla: King of the Monsters. But some would say the studio saved the best for last when director Andy Muschietti took the stage carrying a raft of red balloons to introduce the first footage from It: Chapter Two. The footage opens with Jessica Chastain's adult Beverly visiting her old childhood home, where its …