iPhone 5 S block no caller I’d calls

You cannot do this using iOS. (You could do this using iOS 13, but your device is too old to use this newer iOS version.)

Perhaps your cellular carrier can help you do this.

Hello try this for calls that come in as unknown

1. Open your Phone app. It's a green app in the lower left corner of your iPhone's home screen. ... 
2. Tap Contacts. ... 
3. Tap +. ... 
4. Type "Unknown" into the first and last name fields.
5. Tap Save. ... 
6. Tap Block this Caller. ... 
7. Tap Block Contact.