I am trying to set stack size to 65000 for all items, but I am not having luck finding the right console command to set all loot, or the right config command. I figured out how to go in game and use the /stackmodifier and click one item at a time and change it, but there are a lot of items in game and I thought I saw the console command GlobalStackMultiplier 65000 but now I am wondering if that was for another mod.

Is there a way to have a console command to change all stack values?

I did go through my config and manually change it, but if there is a way to do in console I would love to know, that way if I wanted to change it from say 65000 to 100000.

This plugin has no console commands. 

I only provide the config to edit Or the UI editor built into the plugin which is only accessible inside the game.

I think you are confusing this with StackSizeController please read the documentation or watch the 2 different how-to-use videos listed on the doc.