SetScaleMode is mentioned in the documentation of StaticBitmap as being supported by <wx/generic/statbmpg.h>.
I had a look, but wx.lib.statbmp.GenStaticBitmap is not based on the C++ version and does not support scaling.
I would like to support ScaleMode in wxGlade, but if it’s only available in C++ I won’t spend time on this.
The generic static bitmap class mentioned there is a C++ class that is not currently exposed to wxPython. It probably would not be too hard to add similar functionality to the generic Python class in wx.lib.statbmp and I would accept a PR that adds that enhancement.