How do I install a NuGet package .nupkg file locally to Visual Studio?

I have some .nupkg files from a C# book that I would like to install to Visual Studio. How can I install them?

Here is what I see in the Add Library Package Reference window showing no packages, with the packages shown in my Options window overlaid on top:

Menu Tools → Options → Package Manager

Give a name and folder location. Click OK. Drop your NuGet package files in that folder.

Go to your Project in Solution Explorer, right click and select "Manage NuGet Packages". Select your new package source.

Here is the documentation.