Hi Allenheathx,
I suggest to drag the lower right corner of your anchor widget to the bottom right of the visible space, so that your anchor fills the whole screen. Then reset the position and size x/y to 0. Your picture should now fill the whole screen independantly of the actual screen resolution, thus your UI is useable for customers with a screen resolution different from 1920x1080.
For more information check: UMG Anchors in Unreal Engine UI | Unreal Engine 5.2 Documentation
and UMG UI Designer for Unreal Engine | Unreal Engine 5.2 Documentation