No, you do not have to cover the entire wall. You can create any sized installation. The determining factors for which product you choose have to do with the size. Anything over 48” in either direction is going to be a “mural”. Murals come in panels where “posters” are one solid piece that is under 48”. Murals have excess material top and bottom to be removed during install. You or your installer would trim that in advance for a mural that does not fill the wall side to side and top to bottom.