Hi @NileshTech-7256, thanks for reaching out to us. This looks like problem with not using correct package/library.
Can you please check your solution and see which packages or references it is using?
Mostly the document you are referring to is using Azure.Cosmos package with version 4.0 whereas the ThroughputProperties class mentioned in example should be using Microsoft.Azure.Cosmos with version 3.11.0.
You can use below command to include this package in your solution by running through command prompt:
dotnet add package Microsoft.Azure.Cosmos --version 3.11.0
Or else you can install it using Nuget Manage Console or through Manage Nuget package in visual studio by searching through the same package.
Please let us know if this helps.