How to set up multiple monitors with your Mac - CNET
Dual iMacs! :) | MacRumors Forums
Dual Monitor iMac Setup : r/macsetups
Use iMac as monitor: 5 Solutions - 9to5Mac
Amazon.com: Astropad Luna Display - Laptop Screen Extender, Turn Your iPad or MacBook into a Wireless Monitor, Portable Dual Monitor Setup, USB-C Port Laptop Monitor Extender Compatible with Mac and Windows :
iMac 27" (Late 2012) display connection to Macbook Pro 13" (2017) - YouTube