It is not necessary to buy a zone ticket. Whether you need to buy it depends on your travel needs and ticket policy. If you only want to visit a specific section, it may be more economical and convenient to purchase a section ticket. But usually, you need to buy a full ticket to take the train. As for buying tickets only, this usually refers to scenic spot tickets. If you just want to visit the scenic spot without taking the train, then you only need to buy scenic spot tickets. Please determine the specific situation based on the actual situation and the regulations of the railway department.