https://www.pcgamer.com/fallout-76-will-have-mod-support-but-not-at-launch/

One of the big questions about Fallout 76 is whether or not it will support mods. Previous Fallout games have enjoyed extensive mod support, but as an online game with an inextricable multiplayer focus, the Fallout 76 situation wasn't so clear. Speaking with Geoff Keighley today, however, Todd Howard assured fans that Bethesda is completely committed to making it happen. 

"We love mods, and so we are 100 percent committed to doing that in 76 as well," Howard said. "We will not be able to do that at launch though. Our goal for launch—this is really new for us—is have a well-running, robust service, and then some period later, we're currently still designing what that service looks like, you'll be able to have your own private world and be able to mod it and do all of that.