Basically, The Service aggregator design pattern is receives a request from the client or API Gateways, and than dispatches requests of multiple internal backend microservices, and than combines the results and responds back to the initiating request in 1 response structure.

https://medium.com/design-microservices-architecture-with-patterns/service-aggregator-pattern-e87561a47ac6#:~:text=Basically%2C%20The%20Service%20aggregator%20design,request%20in%201%20response%20structure.