Saved contacts can be blocked, which means no more calls or messages are allowed. blocked contacts are still displayed in the list and cannot be hidden. alternatively, the phone number can be blocked, which is not visible in the contact list and has the same function.

Android 10 (One UI 2.0)
Step 1:  Open the  Contacts -App
Step 2:  Tap on desired  Contact
Step 3:  Open the  menu
Step 4:  Tap on  Block contact / Unblock contact
Step 5:  Confirm with  Block
  1. Open the Contacts-App
  2. Tap on desired Contact
  3. Open the menu
  4. Tap on Block contact/Unblock contact
  5. Confirm with Block

Samsung Instructions