It depends on the country and state or province where you plan on renting a car. In the United States, for example, most car rental companies require that the driver be at least 25 years old. Some companies may allow drivers who are younger than 25 to rent a car, but they will likely charge a higher rate and may impose other restrictions, such as a limit on the type of car that can be rented. In addition, insurance may be more expensive for young drivers. In other countries, the minimum age to rent a car may vary.
Always check the specific requirements of the car rental company you are considering renting from to ensure that your daughter meets their age requirements and any other restrictions they may have in place.