If SharePoint search results contain a direct link to a document, then that document can be viewed by clicking on the search result. For example, clicking on the search result, "Congratulations" in the search result (left image), opens the document for viewing (right image):

Enabling viewing of search results is done indirectly, as there is no switch to specifically enable viewing of search results. Search results can be viewed in PCC if DRM is enabled for the document in the search result. To configure this, refer to Configuring DRM.