a quik ? on graphics tablets

I have been playing with blender for a couple of years now. And thought I would treat myself to a graphics tablet. (I have been using a mouse so far)
My question is: how do you get your pen to zoom in or out. Im used to using the mouse wheel for that, but there is no button assignment for the middle mouse button.
Am I just stuck with using the key board + and - keys?

ps…I bought a Huion tablet

On my tablet I can use my fingers to zoom around, but with a pen a solution would be to check the Emulate 3 Button Mouse under preferences. Then map Ctrl + Alt + LMB Drag to whatever keys you have to zoom in and out.

Ctrl+ MMB drag, don’t know if your pen has a MMB or assignable buttons.

The Wacom pens have a button on them - you can probably assign it to whatever you want it to do.