Besides pre-ordering, you can also get your hands on a beta code by watching the upcoming CDL Championships scheduled to start on August 22, 2021 (Sunday), at 11:30 A.M. PST. If you tune in to the championships, you have a chance to win 1 of 25,000 Call of Duty: Vanguard beta code drops.
What puts a cherry on top is that if you win a beta code, you will also receive an extra beta code to enjoy early access with a friend of yours. If you want to give this a shot, you need to make sure you are watching the championships on the official Call of Duty League website and not on Youtube. Head over to the official site and log in with your Activision or battle net account. All you have to do afterward is to tune into the live stream.
The winners will receive a notification on the official CDL site and their companion app (if they have it installed on their mobile device). The codes are limited and will be dropped randomly. Make sure you save a spot by tuning into the stream as early as possible.