The groups are sorted alphabetically by default, but you can also sort them manually.

Android 9 | LG UX 9.0
Rearrange -  Open the  Contacts -App
Rearrange -  Tap on  Groups
Rearrange -  Open the  Menu
Rearrange -  Tap on  Change order
Rearrange -  Tap and hold desired  Group
Rearrange -  Drag the  group  to the desired  position
  1. Open the Contacts-App
  2. Tap on Groups
  3. Open the Menu
  4. Tap on Change order
  5. Tap and hold desired Group
  6. Drag the group to the desired position

LG Instructions
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