There are 3 main pattern which becomes an API Gateway feautures, that are; Gateway Routing pattern: Gateway Routing pattern is Route requests to multiple microservices with exposing a single endpoint.

 Gateway Aggregation pattern: It provide to aggregate multiple individual requests towards to internal microservices with exposing a single request to the client. 

Gateway Offloading pattern: It offers to combine commonly used shared functionalities into a gateway proxy services. 

https://microservices.io/patterns/apigateway.html