Which design pattern to apply when I send multiple requests to external services, merge them and then return a response?

Let's assume I have an endpoint that receives a request on endpoint:

[POST] /search?product=Apple

Based on receiving product filter I send multiple requests with different request payloads to external services like WebsiteApple1, WebsiteApple2, ...

Now once I get all the data back from all websites I merge responses into an array and return the cheapest product to end user.

Here what kind of design pattern I should use?