The number of the SIM card (1 or 2) is used as symbol by default on dual SIM devices from LG. Alternatively, the symbol can be changed to private, star, office or heart. In addition to the icon, which can be set separately for both SIM cards, the colour scheme can also be adapted.

Android 9 | LG UX 9.0
Step 1:  Open the  Settings
Step 2:  Tap on  Dual SIM Card
Step 3:  Tap on  SIM card 1  /  SIM card 2
Step 4:  Choose desired  Icon
Step 5:  Confirm with  OK
  1. Open the Settings
  2. Tap on Dual SIM Card
  3. Tap on SIM card 1SIM card 2
  4. Choose desired Icon
  5. Confirm with OK

LG Instructions