Do I need to allow free space as an over provision on MacBook Pro's built-in SSD?
No.
Over-provisioning is transparent to the user, and done at the factory. SSDs normally have more size than can actually be used. Over-provisioning is not something that the user needs to do.

Having said that, SSDs still need to maintain spare space within the volume, in order to have some space to accommodate working files. Between 10 and 15% is usually recommended. Some say as much as 25%.