I’m an Australian currently living in France, I have a 12-month long-stay visa. I want to travel to Croatia for 10 days after my visa has expired. My question is, am I then able to return to France (Paris) after I’ve been in Croatia for less than 24 hours to fly home? (Australia).
You can look into earlier questions like Does tourist visa (90 days) apply after a long-term visa ends in Schengen countries? and UK citizen staying in Schengen after long-stay visa expires to understand the nuances but the bottom line is that yes, you can do that.
Note that since Croatia and France are both in the Schengen area, you should not see any border guards before entering the international terminal to board your flight to Australia (i.e. no full passport check on the way out to Croatia or on the way back to France). At that point, even if the border guards are somehow unhappy about the fact that you switched to the visitor status without a stamp, they would not do anything else than complain and let you board your plane (no fine, no delaying your departure when you are already on your way out).