hdiutil detach /Volumes/Install\ macOS\ Big\ Sur hdiutil convert ~/Desktop/BigSur2021.dmg -format UDTO -o ~/Desktop/BigSur2021.iso Rename the resulting .cdr file to .iso .
# If the installer is in your Applications folder ls -la /Applications/Install\ macOS\ Big\ Sur.app Open Disk Utility or use Terminal:
Stay safe, and enjoy the legacy of Big Sur.
But why “2021”? macOS Big Sur was originally released in November 2020. The 2021 versions (specifically 11.2, 11.3, and 11.4) contained critical stability fixes, better M1 emulation support, and security patches that the initial 2020 launch lacked.