How to link 2 Schema together

I’m doing a simple project consisting of 2 schemas:

  • Schema “Tasks” synchronized through realm
  • Schema “user” is linked between Nodejs and Atlas. REST API via Postman
    How to add a task, the “_id” of that task is also added to the “tasks” array of the “user” Schema.

Does it have anything to do with relationships.
Thank you for your time. If you have any questions about the above question, please reply.