From the menu bar select “Options”, then within the “System” tab under “Video” you should see a bar titled “Expand Zoom.”
Move the slider to adjust the camera's maximum distance from your character.
If you have 'Manual POV' enabled, you can control the in-game camera by using the right mouse button to rotate the camera, and the scroll wheel to zoom in and out (up to the maximum distance you have selected).
If you have 'Auto POV' enabled, you can control the in-game camera just like with Manual POV. The camera will automatically return to its preset zoom and north-facing rotation a short moment after the zoom is adjusted or its rotation is changed.
You can toggle between Manual POV and Auto POV by pressing the associated Hotkey, which can be changed in the Options Menu → GAME tab → Control subtab → Hotkey Settings