If you need to apply in person, you need to go through many processes and write more manuscripts. You can download the relevant documents from the official website of China National Intellectual Property Administration, and write and submit the patent according to the guidelines.
You can also entrust a patent agency to apply, so you only need to provide technical disclosure documents (technical implementation principles, steps and drawings), and the rest of the patent manuscripts are written, submitted, paid and defended by the agency.
The role of the agency is to translate the patent manuscripts and layout claims with specific requirements according to your technical disclosure, which can increase the probability of authorization to a certain extent.