Not sure what you are asking but I would think that you would need 2 player objects to flip between 1st and 3rd person.
The 1st person object would be arms/guns etc positioned appropriately so they stick out in front of the screen. The 3rd person object would be like any other game character.
I think it would be very difficult to get one object that works in both these views ; I think most FPS`s have to cheat a bit on position of the observers arms/weapons to make them actually look right.
"Don`t try to engage my enthusiasm, I don`t have one"