os Monterey

ronbarras36 wrote:

can my iMac retina 4k 21.5 inch 2017 be upgraded to macOS Monterey

Yes.

How to upgrade to macOS Monterey

How to upgrade to macOS Monterey - Apple Support

iMac late 2015 and later

iMac Pro 2017 and later

MacBook Air early 2015 and later

MacBook Pro early 2015 and later

Mac Pro late 2013 and later

Mac mini late 2014 and later

MacBook early 2016 and later

you may also want to read this informative user tip: How to upgrade to Monterey - User Tips