Hi Vikram,
Thanks for the heads-up. But in the link, what I could find is how to restrict type of files to upload in assets(.img , video etc.). My question was to limit the size of pdfs and images, and use custom rules for naming where it won't allow special chars, caps, and spacing. Also there will be separate set of rules for pdf and image.
I tried by navigating to /apps/dam/gui/coral/components/commons/fileupload/clientlibs/fileupload/js/fileupload.js and modified the code (shown in the image), but that gets to applied all assets in general.