Back when Fallout 76 first released, there was a lot of talk about official mod support coming to the game. Nearly two years on, however, and there's been little news or update on the subject, so you'd be forgiven for thinking that Bethesda had quietly swept this one under the rug.
Some limited mods are available for the game, and you can find some of them here on GameFront, but they only affect the local client and can't be seen by other players in the server. They're also not officially supported, meaning you could run the risk of being banned by anti-cheat.
It seems that modding is still on the development team's radar, however. The subject was raised during a Q&A panel for the game during QuakeCon this past weekend, and project lead Jeff Gardiner committed to delivering mod support to the game, stating that "We are definitely still working on mod support, it's coming."
He did, however, go on to explain that adding mod support to the game is a huge task, due to the online nature of the title and, specifically, the client-server nature of the game meaning all players in the server will need all modified content loaded locally on their machines.
Gardiner stated that adding mod support was known as "the heavy lift" internally and that the team had committed a lot of resources into making it happen. It does sound like there's something very real and tangible on the way, then, which is great news to hear.