Whether you need to buy a gas tank to refuel depends on the specific situation. If you have your own gas tank, you certainly don't need to buy it. If you don't have a gas tank, there are two ways to solve it.

One, buy one yourself and go to the gas station to inflate it.

Second, you don't have to buy it yourself. You can rent one from the gas station and pay the fuel tank deposit at the same time. You can only use it yourself.