If you are wondering whether it is possible to unlock ACOG Scope, one of the accessories available in Call of Duty: Warzone and Vanguard well, the answer is no, as Activision does not hold the rights to use this term as explained by the site.
However, if you want to replace the ACOG scope that does not exist in Warzone and Vanguard, well, you are going to be able to equip a scope whose magnification is between 2.5 and 3.5. In this category, you can find the VLK or even the G16.
It is necessary to equip an ACOG type scope in Warzone to be able to complete the challenge "Get 15 ADS kills while having an ACOG optic equipped".
For those who don't know what ADS are, these are kills you'll get while aiming with a scope.