don't be afraid about differencies between your and my config.txt file.
Just add with an editor (use notepad or notepad2 as editor, because it is important that the end-of-line info is written in Linux standard.)
So just run windows notepad and add the lines
#Enable 12v gpio output
just ahead of the section [all].
Note that lines beginng with an "#" are commentary lines, so these lines have no effect.
Give it a try, and reboot your Pi4. It will work.