https://wccftech.com/get-fallout-76-beta-code-pre-order/

The Fallout 76 beta isn’t active yet, but it may be available in a few months considering that the full game is coming out mid-November.

In case you’re looking to ensure a spot for yourself in the upcoming test, Amazon is already sending out Fallout 76 beta codes if you pre-order the game. It should be noted that the pre-order doesn’t bill you yet and it is indeed possible to revoke it after receiving the beta code. In case you do get a beta code, you’ll have to redeem it here.