Fallout 76 is the latest Fallout adventure, and it's the earliest game in the Fallout timeline. Previous games in the series mention Vault 76 as one of the earliest bunkers to be opened -- a little more than 20 years after the bombs dropped, and Bethesda confirmed that on the stage at E3 2018.
That means players in Fallout 76 will be seeing a world ravaged by the aftermath of nuclear war, but not ravaged by time — making them among the first survivors of the Great War. And most importantly, the first survivors to start rebuilding society. It also means less time has passed since the bombs dropped