You said you want to compare report in PDF. Katalon Studio does not provide any built-in support for it.
But If you write program for yourself you can do almost anything. But let me remind you, if you are going to write program, you should do more of requirement analysis before talking about which tool to use.
You want to compare 2 pdf files. But why you want to compare them? What kind of “Report” you are talking about? Are you talking about Katalon Studio’s Test Suite’s Report? or you have some kind of business report such as Annual Report 2018, Apple?
Can you get 2 files at once from some source storage? Or do you have to get 1 and store it somewhere, wait for some days,weeks,months, and get the updated version of the same title of pdf? How do you want to see the comparison result? — are you satisfied to see the result in the commandline message? or do you want to compile another PDF, or do you want to send it on e-mail? Quite a lot of things to think about you have.
Final question is — does it worth developing?