Does a virtual replica without relevant sort configuration returns the same result as its primary index?

The search results from virtual replicas can appear similar or the same in terms of their ranking strategy as the primary, but we cannot guarantee that they will always be the same as virtual replicas without customization of the sort order still applies its own logic.

It is important to note that the search results from a virtual replica are not exhaustive. This is because the results are limited by the pagenationLimitedTo parameter, meaning that the exhaustiveness of the results may differ from those of the primary.

You may also review the Virtual Replicas and Relevant Sorting documentations.