Currently, you can only export to the defined subfolder for each artboard/screen (all assets go into Images/inspect/filename_without_extension).
We are tracking interest in being able to export to different subfolders, but this isn’t possible today.
Using a forward slash (
/) in a symbol name in Sketch will create additional subfolders when generating asset exports.
For instance, if you name a symbol "Rectangle/Color/Mobile", the folder structure of the asset will look as follows: Inspect > Name of the file > Name of the page > Device type > Rectangle > Color > Mobile > Assets