In addition to the displayed name format, the call list of the phone app on the OnePlus smartphone can be sorted by first name or last name.

Note: This setting is independent of the selected name format.

Android 10 | OxygenOS 10.0
Step 1:  Open the  Phone app
Step 2:  Open the  menu
Step 3:  Open the  Settings
Step 4:  Tap on  Display options
Step 5:  Tap on  Sort by
Step 6:  Choose  First name  or  Last name
  1. Open the Phone app
  2. Open the menu
  3. Open the Settings
  4. Tap on Display options
  5. Tap on Sort by
  6. Choose First name or Last name

OnePlus Instructions