Yes you do get predetermined days off. But, there are a few different versions of what a “day” off is.

Version 1. A day a from 12 midnight till 12 midnight. What most people refer to as a day free off duty. 24 hrs.

Version 2. A predetermined 24 hr period following or preceding duty. As an example, if your duty from assignment or reserve ended at 11am, and you had to be on duty at 11am the next day.... congrats.... you just got a day off.

Version 3. A 24hr period or more free of duty, while on a layover. So, fly a red eye to Atlanta land at 6am and leave the next morning at 6am. You’ll get paid for the flight there and the flight back only. This type of pay doesn’t count toward your min 12 days off, but, for pay purposes, it’s a day off because you aren’t compensated.