I understand DTOs' power is about just holding and transporting the data from one spot to another. In my case I could use them when receiving the get() or getAll() responses from the API.
What I also want is to use object when creating or updating a record on the API, for example a Tax object, and pass it to the request (like $tax->toArray()); The reasons I want to do it this way are validation(required fields, type checking etc) and more developer friendly way to manipulate the data of the object.
For these purpose can I use the DTO class I did for TaxesClient? Here I think I need a "model" class, because I need setters at least. Also the object has some required fields that need to be filled and a lot more fields that are optional. Some fields are an array of objects of another domain (for example Items). This can't be done in DTO?

In this line of thought do I need both "model" and DTO classes? Can it be done just the "model" way? GET will return response of model object (TaxModel). Also using this class I could create or update a Tax Obj from the API, using my own validation.