You can consider going to the retrieval center of China Patent Office to do a patent novelty search, including domestic and foreign documents.

However, please note that if it is discovered, it exists objectively and will definitely affect the patent authorization; However, if it is not found, it does not mean that it is definitely not, because there is a blind spot in the disclosure of patent documents.

If you want to save money, you can enter English keywords on the website of the European Patent Office. The literature database here is relatively complete.