Depth-of-field (DoF) depends on the lens aperture. The more the aperture the shorter the DoF (but better light sensitivity). In case of fixed lenses you can see the aperture (F-number) in spec. Using all parameters you
can calculate and simulate the DoF. In case of ZOOM lens the spec shows maximum aperture. Real aperture with different focus differs. But entrance pupil of motorized ZOOM lens is bigger, in the most positions such lens has bigger aperture and shorter DoF than usual fixed lenses.
Also ZOOM lenses are frequently tested with long focal length (narrow angles). But the longer the lens focal length - the shorter the DoF. The same ZOOM lens with short focal lens set will have much longer DOF. It is optical law.
You can play with the focus distance. The nearer the focus point – the shorter the DOF.