If you’re a current Windows 10 user and that your system meets the minimum requirements for the jump to Windows 11 you will be entitled to a free upgrade from Microsoft. It’s important (if your computer is capable of the upgrade) to install Windows 11 as it will assure future updates when Windows 10 is archived’ by Microsoft.
However Windows 10 users can, if they wish, decline the Windows 11 upgrade and continue to receive current Windows 10 security updates etc. WindowsReport covers this in detail and is certainly worth a read for all Windows 10 users..