If you download a “BO4 APK” today, you’ll likely get one of the following:

Call of Duty: Black Ops 4 was officially released only for the following platforms: PlayStation 4 (Exclusively via Battle.net) Call of Duty Why an Android Version Does Not Exist Technical Constraints

Instead of looking for a fake port, you can play official games that include Black Ops 4 content: Call of Duty®: Mobile - Apps on Google Play

: An older, official spin-off adapted specifically for mobile that includes maps like Kino Der Toten and Ascension.