Scam call on my iPhone

As for all such calls, hang up on the caller, repeatedly if needed.

See the Apple articles below: 

Block phone numbers, contacts, and emails on your iPhone, iPad, or iPod touch

Block phone numbers, contacts, and emails on your iPhone or iPad - Apple Support

Avoid unwanted calls on iPhone -> Avoid unwanted calls on iPhone – Apple Support (UK)

Detect and block spam phone calls -> Detect and block spam phone calls - Apple Support

Block unwanted callers in FaceTime on iPhone

Block unwanted callers in FaceTime on iPhone – Apple Support (UK)

Avoid unwanted calls on iPhone -> Avoid unwanted calls on iPhone – Apple Support (UK)

Answer or decline incoming calls on iPhone

Answer or decline incoming calls on iPhone – Apple Support (UK)

Federal Trade Commission – Fake calls from Apple and Amazon support: What you need to know

https://consumer.ftc.gov/consumer-alerts/2020/12/fake-calls-apple-and-amazon-support-what-you-need-know