This hasn’t been officially announced but the pages and artwork with dates now appear on Amazon.
The film is on a 100 GB disc for the best picture quality with HDR and Dolby Vision.
Over 15 hours of extras, mostly legacy content on the bluray but the 4K disc does have three audio commentaries, a new documentary, Titanic: Stories from the Heart, featuring new interviews with James Cameron, Jon Landau, and Kate Winslet, as well as a new fan art gallery.
Full press release:
https://www.highdefdigest.com/news/show/Titanic/4kuhd/preorder/james-camerons-megablockbuster-titanic-debuts-on-4k-ultra-hd-bluray-december-5th/48467