Yes, you can put a ceiling fan in an RV! You can find RV-specific ones or use any residential ceiling fan, even those from the big-box store.
Your RV’s electrical system has an AC 120V system and a DC 12V system. Appliances and outlets that run off 120V will only work when connected to an electrical post. Without shore power or an inverter, you can run 12V items off your battery!
Aside from the power source, there are some other things you’ll need to consider before buying an RV ceiling fan. Size, weight, and price are good starting points.