Downgrading to Windows 10

I find I need to downgrade from Win11 Pro to Win10. Looking at various YouTube videos which show detailed processes, I’m confused. Some show a very simple method of downloading Win10 from Microsoft and installing it, after which all my files and apps will be in a Windows.old folder. Others show it to be much more complicated, involving buying a hard drive (I have about 1TB of files on my SSD) to back up before removing Win11.

I’d like an expert opinion before I make a stupid mistake. Can anyone advise me – preferably someone who has done this?