It isn't that bad. For this I used the Daz slider "Eyes Size" dialed to I think 30% or somewhere thereabouts. No other changes. It was tempting to release some presets but I assumed everyone knew about Eyes Size. If you don't, just select the character and in the search bar for Parameters type in "Eyes si" and it will appear. It works very well on 8.1.

Irises are a bigger challenge, although the slider for that in Daz is also pretty well dialed in. If you feel the need to monkey around with irises I recommend creating a morph in Blender. If you select the "Iris" material in that program you can do some pretty wild things if that is your cuppa. Make sure you export a wavefront obj in base resolution, make sure you import into Blender using the Legacy mode with "Keep Vert Order" and "Poly Groups" both selected under "Geometry". If you don't do that, your morphs will explode the mesh when you pull them back into Daz.

I still use Blender 2.79, so no need to use the legacy settings.

I have morphed several Daz figures in Blender, with the eye size increased. The problem I encounter is the rigging, mostly, when Daz re-rigs the figure. The eyes often get wonky rigging. Gotta fix 'em in the Joint Editor.

Oh... that.

Here's how you fix that, assuming you're talking about the morphs being split, but this will work for anything where you want a particular part of the mesh to be unaffected:

When you load the body morph, or any morph where you don't want the eyes to get wonky, go to edit mode in the parameters tab. Select the Geometry Editor tool and under Tool Settings, make sure you're in Vertex Select mode. Right-click the morph slider you're working with and go to "Select Morph Vertices". All affected vertices should now be selected. With "Lasso Selection" as your selection type, de-select any vertices you don't want affected by holding down Alt and lassoing them. They will be de-selected. Now, hold down Ctrl and press the forward slash ( / ) key. This inverts the selection. Now make sure the morph slider is a Favorite by clicking the heart icon. Then right click the morph slider again, and choose "Favorites -> Remove Selected Properties From Favorites". Now Favorite the morph again and right click in the preview window and choose "Morph Editing --> Remove Selected Deltas From Favorites". NOW Adjust Rigging to Shape and ERC Freeze.

Or maybe you already knew that. But maybe another developer will read this and go "Eureka!"

I too, will go "Eureka!" 'cause this is indeed new to me. I will likely try this in my next go-around with human figure morphin'. So thanks a lot, Causam3D!

You're welcome!