Yes, you are right, you don't need to change even a single line of code on the server side if you change a client app. OData defines many conventions for the communications between the client and the server. such as:
What the URL looks like if you want to query some data http://services.odata.org/V4/OData/OData.svc/Products?$filter=ID gt 2&$select=ID,Name,Rating,Price&$orderby=Price desc
Which http method should be used to Create/Retrieve/Update/Delete an entity Generally speaking, Post for Create, Get for Retrieve, Patch/Put for Update, Delete for Delete.
What the payload looks like.
How to invoke a function/action
As long as the requests conform to these conventions, the server side always returns the predictable responsese regardless whether the clients is a browser or a mobile device.
I also find the examples for the odata: https://aspnet.codeplex.com/SourceControl/latest#Samples/WebApi/OData/v4/ .
Hope this helps you.