Are there Folder thumbnails? How to make the file thumbnail only a section of the file?

My folders imported from Adobe draw and sketch does not seem to have thumbnails displaying previews of files inside, is that intended? Is there a way to change this?

Also, my Adobe draw files do not take up the entire canvas, I would like the thumbnail to only contain the relavent portion. Originally the files had the correct thumbnail when imported from Adobe draw but after opening them, it changes to the entire canvas. How would I fix this?