Yes. You can use multi-index search with InstantSearch to display results from different indices in the same interface.
With InstantSearch, you set up a main search experience and then use additional index-scoping widgets (for example, Index in React InstantSearch) so that a single search box can trigger searches across multiple indices and display their results.
All indices must be on the same Algolia application for multi-index search to work in a single InstantSearch instance.