The region is taken from the current network that the Huawei device is connected to. When dialing into a network on the other side of the world, the region is also automatically adjusted. It can also be changed manually on the Huawei smartphone.

Android 10 | EMUI 10.0
Step 1:  Open the  settings
Step 2:  Tap on  System & update
Step 3:  Tap on  Language & input
Step 4:  Tap on  Language and region
Step 5:  Tap on  Region
Step 6:  Choose a  region
  1. Open the settings
  2. Tap on System & update
  3. Tap on Language & input
  4. Tap on Language and region
  5. Tap on Region
  6. Choose a region

Huawei Instructions