In the event of a serious problem with your Mac, you may need to reinstall your Mac operating system. There’s a simple way to do this using your Mac Recovery partition or via Mac Internet Recovery.

Exact steps for Intel and Apple Silicon Macs ...

Lastly, if your Mac supports Internet Recovery, then you can use this by holding Option-Command-R at startup instead of just Command-R. This will load the same recovery tools from Apple's servers that ...