You can stream on Max (formerly HBO Max) or purchase the Blu-ray to see the extended cut. Just go in with an open mind—and a memory of the original comic ready to be challenged.
The 2019 film completely subverts this. While Tommy Elliot appears, the man under the bandages is actually (voiced by Geoffrey Arend). In this adaptation, Edward Nygma, dying of a brain tumor, deduces Batman’s identity. He kills Tommy Elliot and steals his face/surgical skills to torment Bruce. batman.hush.2019