If the OTA update isn't showing up yet, or if you are stuck on an older version, you can use the HiSuite application on a Windows PC. Connect your phone via USB, and the software will check the server for the latest authorized firmware for your specific region (CUST).
Updating the Huawei Y9 Prime 2019 is a straightforward process, but regional rollouts can be staggered. firmware huawei y9 prime 2019 stk-lx3 emui 12
Any website claiming "EMUI 12 for Y9 Prime 2019" is either: If the OTA update isn't showing up yet,