Take a Scrolling Screenshot on Mac or MacBook
How can I take a scrolling screenshot on a Mac or MacBook, similar to how it’s done on Android or iPhone?
MacBook Air 13″, macOS 15.3
You don't. Screenshots are an instance in time and scrolling takes longer. What you can do is capture a video of that scrolling and then turn it into an animated GIF or PNG with appropriate software from the Mac App Store.
The shift+cmd+5 or shift+cmd+U and launch Screenshot give you that video capture capability and will write a .mov file to your Desktop. Search for GIF in the Mac Store to find the tool for creating animated GIFs from the .mov video. The more review stars the better.