Hello Joshua,
Esri does publish example maps with symbology for different industries and applications. For example, we are in the process of implementing the Local Government Information Model - (LGIM) this is standardized database scheme with a variety of products consuming the data - such as ArcGIS Online web maps etc. If you explore the gallery the applications will often include the .mxd used to create the underlying map services.
Here is the link to the Local Government Basemaps
The Local Government Basemaps include:
Inside the downloads are .mxd maps that connect to LGIM sample datasets. You can copy this symbology but will need to apply it to your data structures. These maps assume LGIM compliance so you will likely not be able to use all of the symbols or labeling methods as your data is in a different structure.
I would need to search if Esri has templates for specifically the grey canvas and other basemaps. I have replicated these through simply symbology settings and looking up RGB values for colors etc.