UMG Text block wrap to rectangle auto size

I want my UMG Text block to automatically size itself into a rectangle (with the same aspect ratio as the screen).

To do that, I thought maybe I could use Auto Wrap Text and Warp Text At. However, I can’t set Warp Text At at run-time.

Beside in the detail panel, it can only set “Warp Text At” via C++ with it’s slate.