Although we don't currently offer an out-of-the-box star-rating feature as part of our InstantSearch results, many customers using the Algolia For Shopify extension use a 3rd-party plugin (ie: Yotpo) to handle the rating display and then index the rating data via metafields.
It is also possible to write the front-end code within your hits template to display a star rating based on a specified numeric attribute.
The general approach here would be to modify the templates parameter of the hits widget within the algolia_instant_search.js.liquid file so that it contains the star-review code.
Our Customizing InstantSearch for Shopify documentation offers additional guidance for this approach.
Please note that if you modify any of the Algolia files in your theme, then you would need to re-apply these changes if you update to a newer version of the Algolia plugin (because an upgrade overrides your files).