When Merge creates our normalized common models, we write them to our database in the order that they are returned from the 3rd party endpoint. We then make these objects available via our endpoints in the same order that our backend infrastructure wrote them.
Effectively, this means that Merge objects are sorted by the created_at field, the timestamp for when Merge created this object in our database.
For guidance on how to use the created_at to pull data from Merge, please see our syncing guide.