How to edit a widget code?

Question

I use a Latest Portfolio widget, but it can show max 20, but I need 30. While using Inspector, I can see the counter from 1-20, but cannot figure out which file has it. I viewed almost all files but could not locate one, which had so many Divs and P tags. The author said I can use a Shortcode, but I don't know PHP. How to go about? Thanks