I just stepped into the field of designing. I feel confident in making a good design. But, I am confused about doing an actual project. Could you tell me if it is the UX designer who decides what all things are to be in an app/website.

Does he decide the flow of control and do developers follow that?

Could you tell me the steps involved in designing? Where does he start? Does he get all the data and is portraying that data beautifully is all that he has to do?