Yes, it is possible to set up an automatic call decline response on an iPhone. This feature is known as "Silence Unknown Callers" and it blocks calls from numbers that are not in your contact list, sending them straight to voicemail without ringing. This can be a helpful tool for avoiding spam calls and potential scams.
To set up this feature, follow these steps:
1. Go to your iPhone's settings
2. Scroll down and select "Phone"
3. Choose "Silence Unknown Callers"
4. Slide the toggle to turn on the feature
Once this is set up, any calls from numbers not in your contacts will be automatically silenced and sent to voicemail. This feature is available for iPhone models running iOS 13 or later.