There are two options for adjusting the zoom level within your catalog viewing.

Option #1:

Under Design Template > General Appearance> Zoom Level:

Here, you can adjust the Zoom Level. To change the level, simply click on the menu and select your preferred zoom settings.

For reference, 1 = No Zoom, 1.5 = 50% Zoom, 2 = 100% Zoom, etc. 

Option #2:

Under Design Template > General Appearance > Use Flipping Effect:

Next, select the Slide effect & hit save. 

Now when a user clicks, a Zoom bar will appear on the top right corner:

This allows users to Zoom in or out based on their preferences!