"how to download Screensavers for iMac (24-inch, M1, 2021)"

In addition to the savers provided by Apple there are others you can download (many from the app store)

Hi, Jack,

Thanks for visiting the Apple Support Communities. It sounds like you are looking for additional screensaver options for your Mac. We are happy to provide you with some information.

The Apple Support article Use a screen saver on your Mac - Apple Support describes the currently available options for using a screensaver on your Mac.

If the option you would like to use is not listed there, you can let Apple know your feedback here: Feedback - iMac - Apple

Best!