Is there an option of reducing the size of the PDF copy of submissions?

G'day, 

I have created a large survey that includes over 20 fields that allow the user to upload image files. Some of the test submissions have been greater than 15MB in size (pdf format).

Is there a way to make the PDF file smaller? 

I'm sorry, but I don't think this is possible. The size depends on the content of the submissions. It is a standard one. If you want to compress the size, you may consider using the following online tools:

http://pdfcompressor.com/ 

https://smallpdf.com/compress-pdf

https://smallpdf.com/compress-pdf