See the following Apple articles:
Block phone numbers, contacts, and emails on your iPhone, iPad, or iPod touch
Block phone numbers, contacts, and emails on your iPhone, iPad, or iPod touch - Apple Support
Block unwanted callers in FaceTime on iPhone
Block unwanted callers in FaceTime on iPhone – Apple Support (UK)
See also this Apple article:
Recognize and avoid phishing messages, phony support calls, and other scams
Recognize and avoid phishing messages, phony support calls, and other scams - Apple Support
👉 If you receive a suspicious email or SMS text message that looks like it's supposed to be from Apple, please email it to reportphishing@apple.com
To report illegal, obnoxious, unwanted or malicious e-mail from an Outlook.com, Hotmail, Live or MSN account, please forward the unwanted message in its entirety (including the entire message header), to abuse@outlook.com
Gmail -> https://support.google.com/a/answer/178266?hl=en