With iOS 13 and iPadOS you can take a screenshot and immediately begin marking it up with Apple Pencil by swiping up from the bottom-left corner of the screen.
If you don’t have an Apple Pencil, to mark up a screenshot right after you take it, tap the thumbnail that appears in the bottom-left corner of the screen.
When using Markup swipe down near the top of the toolbar to minimise it as shown in these images. To show the full toolbar again, tap the minimized version.
For further detail see AUSOM News, February 2020 here.