Who chooses the box?
Every project has limits of scope- the limits become “the box” the project fits into. Defining these limits is critical to a profitable job and a happy customer.
The important question is who defines the box? If the customer does, you run the risk of doing work that is outside of your skill set, or that you cannot complete profitably.In the end you are the one making the compromises to keep the client happy.
If you define the box, the client is probably not going to get exactly what they are expecting. If they are the compromising, they will expect concessions- either something thrown in or a reduction in price.
As long as both sides understand what they other is giving up to make the deal work, success is possible. But if the customer is making all of the concessions, and still not happy with the result, you probably won’t get called back a second time.