Is it possible to hack the iPhone camera?

Sounds like a "phishing" message. If you click on any "helpful" link, or contact any "helpful" "tech support" people using a number sent in the message, that is when they will scam you and/or get you to install an app on your iPhone that perhaps you really do not want on your iPhone.

https://consumer.ftc.gov/articles/how-recognize-and-avoid-phishing-scams

https://consumer.ftc.gov/articles/how-spot-avoid-and-report-tech-support-scams

Recognize and avoid phishing messages, phony support calls, and other scams - Apple Support

No, all such emails are scams that by criminals. Do not interact with the message or the sender.