This is somewhat problematic. There are many versions of PDF files, some use compression not supported in other versions, so in short, you'd have to save all PDF files in version 1.4 in order to make this widely effective across all PDF files. And that version may or may not be viable for you. This is something you have to check into to see what limitations and/or risks are involved in having PDFs in v1.4 format.
If it turns out that 1.4 is Ok for you, then as I said, this feature is possible. But it's not quick to build. So you'd wind up paying to have it built - unless you know a PHP / WooCommerce developer willing to built it for free.