Iris Enhancements

You haven't mentioned which version of Lightroom Classic you're uisng. If 12.0 or higher, then you can use the People Mask option to auto find and select various parts of the persons body and clothing. This includes the eye whites (Sclera). When the mask is created you jsut use a slider to edit same. I've attached a screenshot that might help.  Also, Julieanne Kost of Adobe demonstrates the People Mask at 18:40 in below linked video.

https://www.youtube.com/watch?v=Qq5qYxbJHIk

Paint in a Brush mask adjustment. There’s already a masking preset called Iris Enhance.

If you need a tutorial, there are many on the web, like this one: