$Output is an object (of the type shown in your microflow). If you put some additional Retrieve actions in your microflow, you'll be able to retrieve all of the child objects. 2 notes:
Hope that helps.
I can't tell what the object names are because they are cut off in this screen shot, but it seems to me that the association I have highlighted below is 'upside down', i.e. it is 1---Many in the wrong direction. Is the returned value the top object shown below or the second object shown below:
Thanks Mike and Ronald. i used both of your approach and able to resolve it. It is an issue with Mapping. i used the auto generated the map and entities based on schema and those auto generated mapping/entities are not working as expected. i have to create a new entity and change some logic is Mapping to resolve the issue.