The zoom/2D/3D toggle is located in the middle right part of the default screen.
Tap it to expand the toggle to 3 separate buttons: zoom in, 2D/3D toggle, and zoom out. This expanded view collapses into the single “±” icon after 5 seconds of inactivity.
The 2D map option displays a classic map view from above.
The 3D view is tilted and shows the map more in space. You can turn 3D buildings on or off in both map views. In the 3D map view, the buildings are shown in space for easier orientation, some landmarks have even 3D models (supported usually in larger urban areas).