Can we apply for a patent for the production line designed by the manufacturer?

yes.

according to the provisions of the patent law, it is everyone's freedom to apply for a patent, and anyone who meets the requirements for patent application can apply for and pass it.

patent literally refers to exclusive rights and interests. The word "patent" comes from Latin "Litterae patentes", which means open letters or public documents. It is a certificate used by medieval monarchs to issue certain privileges, and later refers to the exclusive rights certificate signed by the British king himself. In modern times, patents are generally a document issued by government agencies or regional organizations representing several countries according to their applications, which records the contents of inventions and creations.