Inter service communication in Microservices

I understand the Event-Driven Architecture where a service subscribes to the events for inter-service communication. An event can be triggered when an entity is created/updated/deleted.. but how can inter service communication be achieved in case of GET requests.

For instance: A notification microservice which returns the list of product notifications for the end user - needs to read User's notification preferences (to which products he wants notifications), needs to get the basic product information (product name, price) and the notification service for the notification data itself.

This can be easily achieved by orchestrating all the services (preference service, product service) inside the notification service - but that would result into tight coupling there.

What's the proper way to implement inter-service communication in microservices when the data needs to be fetch from multiple services?