The LG smartphone automatically selects the time zone based on the information provided by the network, but if you do not want to change the time zone manually, you can do so.

Android 9 | LG UX 9.0
Step 1:  Open the  Settings
Step 2:  Tap on  General
Step 3:  Tap on  Date & time
Step 4:  Disable  Set automatically
Step 5:  Tap on  Select time zone
Step 6:  Choose desired  Time zone
  1. Open the Settings
  2. Tap on General
  3. Tap on Date & time
  4. Disable Set automatically
  5. Tap on Select time zone
  6. Choose desired Time zone

LG Instructions