Facets declared through the Algolia Shopify plugin can be configured to be "searchable", "conjunctive" or "disjunctive".
To do this, head to the Algolia Shopify Configuration > Search Options tab > InstantSearch - Results page powered by Algolia > scroll down to the "Facets" section and edit the relevant facets by hovering over them and clicking "Edit".
In the dialog box which opens, please check "Searchable facets" / mark it as conjunctive / mark it as disjunctive.