Yes there is a cron job!

Start here for background reading:
https://wiki.civicrm.org/confluence/display/CRMDOC/Bounce+Handling

And check to see that your: Fetch Bounces scheduled job is ON (and that you have a system cron running). Of course if you're testing (sending Emails that you know will bounce) -> then you can also hit Execute Now for this specific scheduled job. 

[![enter image description here][1]][1]

  [1]: https://i.sstatic.net/KAizf.png

I found all I had to do was to just follow the Documentation: https://docs.civicrm.org/sparkpost/en/latest/install/