https://msfn.org/board/topic/22555-auto-arrange-desktop-icons-setting/

After some more testing, I found out some values to use with FFlags and Sort:

 Auto Arrange off, Align to Grid off:
"FFlags"=dword:00000220

Auto Arrange on:
"FFlags"=dword:00000221

Auto Arrange off - align to Grid On:
"FFlags"=dword:00000224

Auto Arange on, Align to Grid on:
"FFlags"=dword:00000225

Hide Desktop Icons:
"FFlags"=dword:00001220

Sort by name:
"Sort"=dword:00000000

Sort by size:
"Sort"=dword:00000001

Sort by type:
"Sort"=dword:00000002

Sort by Modified:
"Sort"=dword:00000003

For example, if you wanted to enable auto arrange and sort by type:

 [HKEY_CURRENT_USER\Software\Microsoft\Windows\Shell\Bags\1\Desktop]
"FFlags"=dword:00000221
"Sort"=dword:00000002