The Zanzibar white paper from Google in 2019, for example lists top-line rpcs to Zanzibar at around 10m qps, but internal (in memory) cache hits at 200m qps and non cache internal fan-out at >20m qps. Zanzibar of course isn't http, but is a good public example of internal rpc fan-out.

Id expect cloutdflare similarly has some extremely high qps internal services.