What cord do I need to connect a 2020 Mac Mini to a 2012 27” iMacto use the iMac as a display?

Won't work

Use your iMac as a display with target display mode - Apple Support

"iMac models introduced in 2011, 2012, 2013, and mid 2014

The other Mac that you're connecting it to must have been introduced in 2019 or earlier and have macOS Catalina or earlier installed."

Not the 2012 iMac.

shawnn240 wrote:

Thank you! Is there a cable needed to connect the 27” iMac to the MacMini? Or does using the share screen work off Bluetooth or wi-fi? Sorry, I’m not super savvy with technology. If you could just explain how the connection works, I would very much appreciate it.

WiFi or ethernet. Ethernet is preferred for best performance unless you have one of the new, expensive ludicrous speed WiFi routers.

Turn Mac screen sharing on or off - Apple Support

Best solution is to simply buy a display for your Mini and sell your iMac to help pay for it.

Use Screen Share.

I've found it to be very productive to connect my Mac Mini to my 27 in iMac.

After you turn on the Screen Share option in the SHARING section of System Preferences in both devices, make sure both devices are on the same wifi network or LAN.

You get much more than just a monitor from the iMac, since you can have it use it's processor, SD card reader, storage, etc.

Good luck!