There is no Cloudflare CDN node in mainland China. The speed of accessing websites proxied by Cloudflare CDN is very limited. Using a third-party tool, I can get a Cloudflare CDN IP with relatively low latency. I hope that all the websites I access from Cloudflare CDN will be accessed through that IP with low latency. In the HTTPS request, how should I set the request content to ensure that I can access all websites using Cloudflare CDN through the fastest IP?
Outside Mainland China all Cloudflare IP addresses are anycast so announced from all locations. (Different plans use different IP addresses to allow for prioritisation). However routes out of mainland China are often congested so performance is limited by that and the routing decisions of the China ISPs - a lot of traffic is sent to LAX in my experience.
Cloudflare does offer China nodes but that requires an Enterprise plan, plus China network add-on, plus an ICP license.