Do I need to install antivirus on my iMac running macOS Sequoia?

No. Most of the contributors here would agree that installing any anti-virus or macOS optimizing software is a very bad idea.

A reference from a level 10 contributor has provided this info:

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

PS - 15.6.1 has is available for download.

DOMLIN wrote:

Do I need to install some sort of antivirus spyware?

[Re-Titled by Moderator]

Original Title: using iMac 24", running Sequoia 15.6,

Third party AntiVirus is not recommended— it typically does nothing but add issues to the macOS and competes directly with Apple’s own built in security:

macOS antivirus - Protecting against malware in macOS - Apple Support

macOS - Security - Apple https://www.apple.com/macos/security/

Apple Platform Security - Apple Apple Platform Security - Apple Support

Verify your software is up to date…

The current stable release of Sequoia including bug fixes, security updates is macOS 15.6.1

Keep your Mac up to date - Apple Support

Keep your Mac up to date - Apple Support