Using Your iPad as a Display + Apple Pencil
One of the biggest macOS Catalina features is called Sidecar. This allows you to use your iPad as an external display for your Mac. You can connect wirelessly, so this works at home as well as on the go, to amp up your productivity. You can also use this tech to work on your Mac with the Apple Pencil.
The display option lets you extend your desktop or mirror the display. This makes it easy to either add more space or get a portable version of your Mac's display that you can take to the couch or just hold in your hand. I plan to use this with an Ergotron iPad mount to add another display on my desk. I'll also use it when working remote at trade shows and on business trips.
Select Mac Apps will allow you to use Sidecar to draw and mark up items on your Mac using the Apple Pencil on your iPad display. This can replace a dedicated drawing tablet in some cases and is a really amazing free feature.