You can assign special Vibration Patterns for phone calls or FaceTime calls from important contacts. Choose from existing patterns or create a new one.
Create a new vibration pattern: If you’re already editing a contact, tap vibration and then tap Create New Vibration.
You can also go to: Settings > Sounds > Choose a Sound > Vibration > Create New Vibration.
Set a custom pattern as the default: Go to Settings > Sounds > Choose a Sound > Vibration and choose a pattern.