I have 5 document libraries inside my SharePoint online site collection, and i create a search result web part to filer and search documents from the 5 document libraries (the 5 document libraries uses the same content type). but i am not sure if i can add a refinable inside my search result web part, to filter the documents based on their library name or title, i can see there is a managed property for ListID, but not sure if i can user or create a managed property for the List Title/Name?
There is no refiner that is pointing to document library name. As a workaround you need to create a new hidden column in the document library, give it default library name. Add a managed property tagging this column and then after the crawl add it to the refinement panel. refer here.