iMac (Retina 5K, 27-inch, Mid 2015) can this model be upgraded to the latest version

Your 2015 iMac is upgradeable to Montere it is included in this

How to upgrade to macOS Monterey - Apple Support

as: iMac introduced in late 2015 or later

Somes things about upgrading:

Do you have enough free disk space?

If upgrading from macOS Sierra or later, your Mac needs 26GB of available storage to upgrade. If upgrading from an earlier release, your Mac needs up to 44GB of available storage.

Also uninstall any antivirus and "cleaning" apps before trying installing again.

Further, you need an Apple disk installed to upgrade to Monterey since the upgrade includes an update to the Mac's firmware. That update looks for an Apple disk and write to the dick to do the firmware update. The install will terminate or freeze if no Apple disk.

Some users have problem with skipping upgrade versions and even not updating to the latest version of Big Sur. Some users have experienced problems by skipping upgrade,es like going from 10.15 to 12 (Monterey).

No.

(213398)

A mid-2015 iMac isn't a late-2015 iMac.

(213403)

+1

I was agreeing with Niel.