New contacts can be added to the address book or Contacts app on Xiaomi devices. In addition to name and phone number, you can add a lot of other information, such as work location, email, address, birthday (displayed in the calendar), relationship, website, memos, and even set a unique ringtone for each contact.

Android 10 (MIUI 12.0)
Step 1:  Open the  Contacts app
Step 2:  Tap on  Add
Step 3:  Choose an  account
Step 4:  Enter a  name
Step 5:  Enter the  phone number
Step 6:  Tap on  Save
  1. Open the Contacts app
  2. Tap on Add
  3. Choose an account
  4. Enter a name
  5. Enter the phone number
  6. Tap on Save

Xiaomi Instructions