Are there bigger taxis that can accommodate 5 people and 2 big luggage from baiyun airport ?

Well, as I know, most regular taxis can only allow four passengers one time. So according to the situation, you need two taxies.

Or you can hire a mini van from the airport. As I know, TravelChinaGuide provides pick-up service. If interested, their contact information is traveltravelchinaguide.com.