The date is determined on the LG device by the network. This is done automatically, although the date can also be changed manually. Before doing so, the automatic function must be deactivated.

Android 9 | LG UX 9.0
Change date -  Open the  Settings
Change date -  Tap on  General
Change date -  Tap on  Date & time
Change date -  Disable  Set automatically
Change date -  Tap on  Set date
Change date -  Choose desired  Date
Change date -  Confirm with  OK
  1. Open the Settings
  2. Tap on General
  3. Tap on Date & time
  4. Disable Set automatically
  5. Tap on Set date
  6. Choose desired Date
  7. Confirm with OK

LG Instructions