the first method: you can ask the China National Intellectual Property Administration Patent Office for the patent "application document" (free of charge), or you can download the patent "application document" from the China National Intellectual Property Administration website (address: /sipo/zlsq/zlsqbg/default.htm). As for what application documents are needed, since the invention patent is different from the utility model patent, you should first ask China National Intellectual Property Administration what kind of invention your invention belongs to (the consultation method is below), and then directly ask him what application documents he needs and the address of the Patent Office.
I suggest you search for a patent first (China National Intellectual Property Administration's patent search website: /sipo/zljs/default.htm). You can learn how to use it slowly by clicking the "Instructions for Use" below. If you don't find the same patent after searching, you can apply! But you should first make sure that someone is willing to spend money to buy your invention (few people are willing to spend money to buy an idea now, unless your patent is monopolistic), because it costs money to apply for a patent. Now there are many applications for patents, but only a few can be sold.