Shut down your Mac
Turn it on and immediately press and hold Command (⌘) + R
Keep holding the keys until you see the Apple logo or a spinning globe
Release the keys when the Recovery screen appears
For Apple silicon Macs, press and hold the power button until Startup Options appears
Click Options, then click Continue
If needed, use Option + Command + R to enter Internet Recovery
If needed, use Shift + Option + Command + R to reinstall the version of macOS that came with your Mac or the closest available version