Yes! MAVIS supports both digital and optical zoom.
Digital zoom is available on all phones and works in 1080p. To access the digital zoom use a tap, tap & hold then drag gesture on the viewfinder.
Optical zoom works on the iPhone 7 Plus, iPhone 8 Plus and iPhone X. You can select between either a wide-angle or telephoto lens. To alternate between each lens just double tapping the viewfinder with two fingers.
For more information about zooming (including the zoom gestures) take a look at this dedicated support page: Digital & Optical Zoom