This article that Q posted on May 11, 2018 confirms that they have the technology to identify a child victim in porn even if that child is now grown. Here is an excerpt from the article.

Last June, the system managed to build a facial profile of a missing girl in northwestern China’s Xinjiang Uyghur Autonomous Region simply by scanning an old photo of the six-year-old taken several years ago. Before long the girl was found after she was spotted by a surveillance camera in front of a market.

https://nationalinterest.org/blog/buzz/chinas-surveillance-system-can-scan-population-1-second-25743