Once you’ve done that you can add handwriting or sketches and you can even use a ruler for drawing. With the app “Snip & Sketch” you can take a screenshot of the whole screen or you can cut out a part of your screen. And you can adjust the pressure sensitivity which can be useful if you feel like you’ve got to press too soft or too hard. Inside that app, you can see how much battery your Surface Pen has left. And if you’ve got problems with yours, that’s where you can download the Surface Diagnostic Toolkit. With that one, you can see which Surface you are using. The first app that you don’t need to use daily but should know about is the Surface app. Most of them run on the Surface Pro X as well.
By the way, most of these apps work with the Surface Pro 6, Pro 7 and the Surface Go.