On the invoice can I add Mass(Kg) and LxBxH cm. I want to do invoices for a courier company.
You cannot add fields on a line by line basis. Nor can you have Manager perform the LxBxH calculation for you. But you could add custom fields that would show at the bottom of the invoice. Obviously, that would only work for single-package shipments. Your other alternative would be to custom code a sales invoice view template.