Use the zoom controls in the bottom-right corner of the canvas
Click the plus button to zoom in
Click the minus button to zoom out
Use the zoom percentage dropdown to select a specific zoom level
Press Ctrl and scroll up with your mouse wheel to zoom in
Press Ctrl and scroll down with your mouse wheel to zoom out
On Mac, press Command and scroll with your mouse wheel
Use the trackpad pinch gesture to zoom in or out
Press Ctrl + plus to zoom in
Press Ctrl + minus to zoom out
Press Ctrl + 0 to fit the design to the screen