where is the full macOS installer for Big Sur 11.6 NOT the update

Like others, I'm having trouble finding the full install file for macOS 11.6. A few notes:

when I run "  softwareupdate -l  " – I get:

  Finding available software

  Software Update found the following new or updated software:

  * Label: macOS Big Sur 11.6-20G165

            Title: macOS Big Sur 11.6, Version: 11.6, Size: 2575888K, Recommended: YES, Action: restart

but size is only 2.6GB so maybe this is just the updater?

I get a message that file not found when I run this:  

" softwareupdate --fetch-full-installer --full-installer-version 11.6 "

I want to make an installer on an external disk (typical thumb drive).

Thanks