Your Windows 10 product key serves as proof that you actually own Windows 10, and might need to be entered when you reinstall ...
You might also see a notification in the upper right corner of the "Updates" tab in the Settings app saying your device is ...
If you're building a new workstation or gaming PC or acquired a device that doesn't have an operating system, you will have to install Windows 11 manually. Although if you have never done it before, ...