Fallout 76 is planned to release Nov 14th. Early release B.E.T.A. (Break It Early Test Application) for Xbox One starts Oct 23, and Oct 30 for PlayStation 4 and PC.
Taken from the game’s website:
Bethesda Game Studios, the award-winning creators of Skyrim and Fallout 4 , welcome you to Fallout 76 , the online prequel where every surviving human is a real person . Work together, or not, to survive . Under the threat of nuclear annihilation, you’ll experience the largest, most dynamic world ever created in the legendary Fallout universe.