Pre-Order If You Want Call of Duty: Black Ops 4 Beta Access
There is a private Call of Duty: Black Ops 4 beta later this year that will allow you to try out the game before it arrives. This is as close as you will get to a Black Ops 4 demo.
You need to pre-order for access to the Call of Duty: Black Ops 4 beta. In previous years we've seen multiple codes sent to one pre-order so you can invite friends and developers have opened up the game to everyone for a stress test, but ultimately you will need to pre-order if you want access.
If you pre-oder Call of Duty: Black Ops 4 for beta access and you don't like it, you can cancel you pre-order as long as you didn't pre-order digitally. That's something to keep in mind.
Expect more Black Ops 4 beta details this summer, including early access for PS4 and likely an extra weekend for PS4.