Can I expand the Y-axis of trend data on the SMARTDAC+ GX/GP series' Universal Viewer?

Yes. To configure display group settings, on the View menu, click Display Group Setting. Or, click the Display Group Setting button. Use Scale (max, min) to zoom the scale in or out. For details, see section 3.1.2, “Setting Display Group Details” and 3.1.5, “Setting the Y-Axis” in user's manual (IM 04L61B01-01EN).