The canvas has a concept of a Camera, this allows you to move freely around your work area and zoom in and out
To move the canvas, you can select the Move Canvas tool, then drag to move around the canvas
If you use a mouse with a scroll-wheel, you can scroll the wheel to zoom in and out.
If you are using a trackpad, you can use a two-finger gesture to zoom in and out
Alternatively, you can use the slider in the timeline toolbar