The “scaling” itself is not really the problem. The libraries handle that.
To be legible, the whole UI layout on a high-DPI is upscaled(*) to use four times as many pixels (double width and height)
(*) may be the wrong term. It’s not really scaled like in a photo-editor, as that would be blurry and not look better than a low-DPI display.
As a result, the window occupies four times as many pixels.
To simulate that on a normal screen, either cut the resolution in half, or just use the top left quarter of the screen. Or have a centered wallpaper with 360x720 and align the window on it.
If the application cannot be constrained to that size or cannot be used nicely, then it needs to be made adaptive, to present the content differently when screen space is limited.
In the development chronology you can find several updates on that work, for example this one: