Partial Sync Relationships


Is it possible to partially sync related objects?
It seems like if I sync a particular object, all of the related objects are synced too.
Now if there are millions of related objects, they will all be synced - can we control this? So only the required are synced

For example.
An object has
let posts = List()
There are millions of posts in this list. A user does not need to sync all of them, just needs the latest 100