The first foldable phone from Samsung will most likely be named Galaxy X, and Wall Street Journal informs that it is supposed to be launched in early 2019 with a flexible 7-inch display that can be folded like a wallet. It can either hide the display completely or split the main display into two smaller screens.
https://www.notebookcheck.net/Samsung-s-foldable-Galaxy-X-coming-in-ealry-2019-according-to-Wall-Street-Journal.317318.0.html