Contacts are sorted by first name by default on the LG smartphone, but the settings allow sorting by last name as well.

Android 9 | LG UX 9.0
Step 1:  Open the  Contacts -App
Step 2:  Open the  Menu
Step 3:  Tap on  Contacts settings
Step 4:  Tap on  Display
Step 5:  Tap on  Sort contacts by
Step 6:  Choose between  First name  and  Last name
  1. Open the Contacts-App
  2. Open the Menu
  3. Tap on Contacts settings
  4. Tap on Display
  5. Tap on Sort contacts by
  6. Choose between First name and Last name

LG Instructions