With Sidecar, you can extend the workspace of your Mac by using your iPad as a second display. The extended workspace allows you to use different apps on the different screens, or to use the same app across both screens, but control different aspects of it. For example, when you use the same app on both screens, you can view your artwork on your Mac while you use Apple Pencil and an app’s tools and palettes on iPad.
You can use Sidecar with your Mac and iPad.
Make sure that your devices are within 30 feet (10 meters) of one another,
For more troubleshooting tips, see the Sidecar system requirements in the Apple Support article Use an iPad as a second display for a Mac.