Can you boot into recovery mode on an older iMac running a newer version of OS X (10.8)? I'm running OS X 10.8 on an iMac which is from 2008, and I can't seem to boot into recovery mode. Command-r doesn't do anything- the computer simply boots normally every time. Although OS X 10.8 certainly does support recovery mode, I'm wondering if the problem might be that I'm using an iMac that was built before the feature was added to OS x (it was added with 10.7 Lion in 2011, my iMac is from 2008). Is it possible that the hardware is preventing me from booting into recovery mode, or is it solely a feature of the operating system, and should work on older iMacs as well?
I believe the issue is that recovery mode was introduced in 2011, you are indeed correct.

If you have access to another Mac you could create a bootable macOS installer and boot from that