If desired, we can create groups or labels in the Contacts app on the OnePlus smartphone, for example, to manage family members or work colleagues and send e-mails or group messages (SMS messages).

When a group is created, a group name is immediately specified, but it can be edited or changed at any time.

Android 10 | OxygenOS 10.0
Create contact group -  Open the  Contacts app
Create contact group -  Open the  menu
Create contact group -  Tap on  Create label
Create contact group -  Enter a  name  and tap  OK
  1. Open the Contacts app
  2. Open the menu
  3. Tap on Create label
  4. Enter a name and tap OK

OnePlus Instructions