softwareupdate --list-full-installers
Finding available software
Software Update found the following full installers:
* Title: macOS Monterey, Version: 12.0.1, Size: 12128428704K, Build: 21A559
* Title: macOS Big Sur, Version: 11.6.1, Size: 12428472512K, Build: 20G224
* Title: macOS Big Sur, Version: 11.6, Size: 12428553042K, Build: 20G165
* Title: macOS Big Sur, Version: 11.5.2, Size: 12440916552K, Build: 20G95
* Title: macoS Big Sur, Version: 11.5.1, Size: 12440158909K, Build: 20G80
* Title: macOS Catalina, Version: 10.15.7, Size: 8248985973K, Build: 19H15
* Title: macOS Catalina, Version: 10.15.7, Size: 8248854894K, Build: 19H2
* Title: macOS Catalina, Version: 10.15.6, Size: 8248781171K, Build: 19G2021
* Title: macOS Mojave, Version: 10.14.6, Size: 6038419486K, Build: 18G103
and then pick the desired one with a command like:
softwareupdate --fetch-full-installer --full-installer-version11.6.1
Each download version will been saved in the application folder