How can I increase the thumbnail size when using Safari to upload an image to a website?

I upload many images to multiple websites and when using Safari to upload these images, the thumbnails are so small I can barely make out what the image is. I can easily figure out how to increase the thumbnail size when viewing them in Finder and set the default to my liking, but I cannot seem to find a way to do this in Safari. The last topic I saw on this was form 2013 and have not seen any update. Is there a way to do this?