Hi Mohit,
This is a question which can be asnwered by Client as per the structure of their business as to what they have defined as Profit Centers in the business.
For example : If you have defined Plants as Profit center in your organisation, then yes, when you extend to different plant, the profit Center will change.
If you have defined Products/Product line as Profit Center, then it may not change even if you extend it to different plant. etc...
Regards,
Kavita