Or you can use Option-Command-R during the startup process to be offered either the latest macOS that is compatible with your Mac, or in some cases the macOS that came with your Mac or the closest version still available.
When you install macOS from Recovery, you'll get the current version of the most recently installed macOS, with some exceptions: When the new owner starts up the Mac, they can use their own information to complete the setup process. If you're selling, trading in or giving away your Mac, press Command-Q to quit the assistant without completing setup. When the installation is complete, your Mac might restart to a setup assistant. Your Mac might restart and show a progress bar several times, and the screen might be empty for minutes at a time.
Step 4: Reinstall a new copy of macOS Big Sur If Scheme is available, select GUID Partition Map.If your Mac is using APFS, select APFS from the format list.