Adding WSDL files from file directory
No answer was accurate for me, but for VS2019, to add a wsdl file as a service reference, I right-clicked on the project -> add -> connected services -> Microsfot WCF Web Services reference -> browse the .wsdl file. This will generate the code to call the referenced services.
Right click on project and select add Web Reference
In dialog Box type on the URL File://test.xsdl
Right click on the project, click on 'Add Service Reference'. Add the path to the WSDL file. It will generate the code to call the service for you.