Do I need Norton 360 for Anti-virus, -spyware, -botnet, etc. for my Mac

Nope. Not outside of corporate networks with endpoint security requirements, or similar. For most of us? Use the built-in anti-malware provided by Apple. Those products are a common source of issues, and some of the better-known packages uploaded and re-sold all your web activity and your online purchases. Others just cause instabilities, crashes, and other messes. Network connectivity issues too, as many of these add-on apps insinuate themselves into connections, and can disrupt those. And those generally don’t protect against the two most common messes—stuff the user installs deliberately that’s adware or such, and efforts to scam you out of your credentials; of phishing and such.

Effective defenses against malware and other threats - Apple Community

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

Do not install any third party anti virus apps.

macOS - Security - Apple

Set up your Mac to be secure - Apple Support

Protect your Mac from malware - Apple Support

https://discussions.apple.com/docs/DOC-8841