Anycast ip.
You have a sole ip address. All traffix routed to nearest PoP. The PoP makes the call on where and how to route the request.
Lookup google front end (GFE) whitepaper. Or thd google cloud global load balancer
That front end server that lives in the PoP can also inspect the http packets for layer 7 load balancing.
https://cloud.google.com/load-balancing/docs/load-balancing-...