Depending on what you want to achieve with Recovery Mode, you can hold down the following keyboard shortcuts immediately after powering on or restarting, assuming you have a Mac with an Intel processor:
- [CMD] + [R]: Use this combination if you want to install the version of macOS previously installed on your Mac. This will not update your system version but use the one you had installed before the restart.
- [OPTION] +[CMD] + [R]: Use this combination to update your system to the latest version of macOS that is compatible with your Mac.
- [SHIFT] +[OPTION] + [CMD] + [R]: This combination installs the version of macOS that came with your Mac, or a version that is closest to that version (should it no longer be available as a download).