Connecting my 2020 Macbook Air to my 2021iMac display
Can I connect my 2020 Macbook Air to my 2021 iMac to use it as the display?
MacBook Air 13″
No.
Review the document: Use your iMac as a display with target display mode - Apple Support
Target display mode is a feature available with late 2009-Mid 2014 iMacs. The display Mac has to be running macOS High Sierra or older and the signal producing Mac has to be running macOS Catalina (ca. 2019) or earlier.
