How to modify application scale with BP?

This might be really simple but I can’t find the solution…

I’m looking to scale all my Widgets depending on the physical screen size (not resolution).

In Project Settings->DPI Scaling there is a variable called “Application Scale” that does exactly what I need. The tooltip even clarifies it further: “An optional application scale to apply on top of custom scaling rules. So if you want to expose a property in your game title, you can modify this underlying value to scale the entire UI

BUT… How do I actually modify this value via BP? I don’t manage to find a node and I don’t manage to find a command that adjusts this value. Can it only be changed in the project settings and not at runtime?