I would recommend you to search this on internet. You will get enough link to download the question papers. Now in general such papers aren't available online so you can go for the book stores and get the question paper books as published by different publisher.

You can visit the link below if you want to buy books online from amazon:

https://www.amazon.in/s?k=karnataka+police+constable&ref=nb_sb_noss

I hope this answer helps. All the very best for your future endeavors!