Is there a plugin to add a map behind the spatial results? Using SSMS 18.5.1 and dealing with spatial results. I would like to visualize this data against a map of the world using Google Maps, Bing Maps, or any other mapping software. Is there a plugin or a way to accomplish this within SSMS?
There is but as you have found out it is rather limited. I think you will have to try another tool / software Power BI has quite good geographical support or you could try real GIS software such as ArcGIS or MapInfo or one of the many opensource GIS projects.
Can't give a proper answer re BingMaps or Google maps, pretty sure you need to write some code and also purchase some cloud credits for the relevant service.