Hello @Otthercreek,
There are some pupil morph targets set up in the face mesh, but it is very subtle, I found you can get more extreme results if you change parameters inside the eye material.
Be sure to set up the DynamicMaterialInstances in the Construction Script too. (There are a few set up for eyelashes, so just copy the format)
As an experiment I also recorded myself while figuring this out. Let me know what you think. (The mic sounds weird for the first minute because it was picking up my laptop fan, but I was able to quiet the fan)
Figuring out how to Control Pupil Size in Metahuman Eye Material