Hi and welcome,
The first two most important and common issues for a new owner of a 9 year old RV - especially if it's been in storage - is to check the DOT Date codes on the tires. Hopefully, those are not the original tires that came on the RV. The tires on an RV "age out" between 6 and 7 years. It doesn't matter what the mileage on them registers. If the date codes are 6 years or older you should plan to replace all 6 of them before any driving or usage.
The other is the Chassis battery condition and the House Battery Bank's condition.
The chassis battery starts the RV, operates the leveling system, the slides and generally (but not always) is the battery that starts the generator. Obviously, this battery needs to be in good condition with water in the cells and clean, solid cable connections.
The House battery bank powers all the 12v devices in your RV when you are not plugged into shore power or running the generator. Keeping these batteries in good condition is vitally important for using the RV on camping trips.
Obviously, there are a great many other systems that need checking out and insuring that they've been maintained properly. But these two are generally the first things on the list.
Date code info - this presenter says "up to 10-years" but that's not a safe or prudent lifespan. A flat tire on the highway on a Class A can be deadly. Using 6 to 7 years as a max is the safe way to go. And, less than that if the tires show any crazing or cracking on the sidewall.
