https://www.gamespot.com/articles/e3-2018-fallout-76-details-new-monsters-and-nuking/1100-6459795/

Fallout 76 received the most stage time at Bethesda's E3 2018 showcase, but even after the deep dive it left some questions unanswered. More details have emerged that shed light on the types of monsters we can expect from this version of the wasteland, as well as how your player character will level up and interact with other humans.

In NoClip's Making of Fallout 76, Bethesda developers talked about how the new time period is opening up new monster design opportunities. Since it's closer to when the bombs fell, they reason, their mutations can be bigger and stranger.