If your models are initialized in separate services and you need to perform a JOIN query in a particular service, you can handle this in multiple ways:

1. Direct Database Query: Use raw SQL queries or ORM-based joins if all models share the same database.
2. ORM Associations: If using Sequelize or TypeORM, define relationships and include associated models.
3. API Calls Between Services: Fetch data from other services via REST API or GraphQL.
4. Event-Driven Approach: Sync required data using message brokers like Kafka or Redis Pub/Sub.

For a detailed guide, check out this blog: How to Add JOIN Queries in Services with Separate Model Initialization