Currently, on the GFV studio sleeps five. But none of the other studios will sleep five at this time.
If you book a one bedroom villa that officially only sleeps four, you will have to provide your own sleeping space for the fifth person. They will not provide a rollaway or cot or sheets and blankets. You will need to bring your own air bed.
Like DebbieB said, the value villas are the exception at this time. You cannot have a fifth person age three or older in those one bedroom villas.