In theory, to do so, you need to use Classes and Representations.

First create your class then tick the "Searchable" box for the class and the same "Searchable" box on the properties you want to have in your index.

Then create the Representation and tick the "Used for search results"

Now the Class will appears in the Entities for the Search index management.

Now it's your turn to try it !

I am not sure of what settings to set.

I created a class and representation however the class can not be selected