There is no downgrade option with a new system pre-installed Windows 11. This system most likley includes an OEM license which also means you would not be able to do a clean install and have your license work. I believe a Windows 11 key would work to activate Windows 10, but you would need a retail license.
Be warned that Windows 10 will be end of life and will no longer receive updates starting next year.
You can run the following command to check what type of license you have. If it does not say retail (for example OEM or OEM DM) you would not be able to do a clean install with a downloaded copy of Windows 10
