Getting the macOS installer for my iMac (Late 2012) written by Jack-19

I am trying to

"How to Setup and Use an External SSD as a Startup Disk on a Desktop Mac"

I found the above instruction on this support group. It was written by Jack-19.

I have been working through it and I am now currently at "Get the macOS Installer.

My iMac is Late 2012 and it tells me to download macOS Catalina. OK up to this point.

Then it tells me to go to: "How to get old versions of macOS - Apple Support.

When I go to Apple Support, I am confused.

• macOS Big Sur can upgrade Catalina, Mojave, High Sierra, Sierra, El Capitan, Yosemite, Mavericks
• macOS Catalina can upgrade Mojave, High Sierra, Sierra, El Capitan, Yosemite, Mavericks

Really? Does Big Sur upgrade Catalina?

I have an iMac Late 2012. It is updated and currently has macOS Catalina 10.15.7