Hello.
How to change the size of the progress bar is already shown in BP and in C++.
Note that in order to use CanvasSlot, the parent of the progress bar must be a CanvasPanel!
If it is not, you can “SetSize” it by traversing the parent of the parent, and further parents, and finally getting the widget that is a child of CanvasPanel.
The C++ classes are UCanvasPanelSlot and FAnchorData.
Need more explanation? Or help?
I think Anchors and Slots in the UMG UI Designer Guide might be helpful.
Thanks.