Zoom In and Zoom Out
In Page View, you can zoom in and out of your page or document with the Zoom In and Zoom Out controls in the toolbar. You can also use trackpad gestures on your Mac.
You can zoom in or out using the Scale item in the toolbar. Click into the Scale field to change the percent manually. If the Scale item is not in your toolbar, add it by customizing your Toolbar.
In the Sidebar, you can increase or decrease the size of the thumbnails with the slider found at the bottom of the Sidebar.