Open Control Center on your Mac
Click Screen Mirroring
Select the device or display you want to mirror to
If prompted, enter the AirPlay code
To mirror an iPhone or iPad, make sure both devices are on the same Wi-Fi network
To mirror to an external display, connect the display with the correct cable or adapter
To stop mirroring, open Control Center again and click Screen Mirroring
Select Stop Mirroring or disconnect the display