From AI search:
In California, driving an RV over 40 feet in length requires a Noncommercial Class B license if the vehicle is a single-unit motorhome (up to 45 feet). If you’re towing a trailer with a Gross Vehicle Weight Rating (GVWR) over 10,000 pounds or a fifth-wheel trailer over 15,000 pounds, a Noncommercial Class A license may be required.
However, California has a reciprocity policy for out-of-state drivers. If your home state’s driver’s license legally permits you to operate an RV over 40 feet, you can drive it temporarily in California without obtaining a California-specific license, provided your home state’s license is valid and covers the specific RV type.
In other words, if you can legally drive your rv in your home/licensed state you can legally drive it in California.