This thread got me thinking. How many of these celebrities have such beautiful eyes and how much of it is enhanced in some way through movie effects? I don’t think I’ve ever seen such bright eyes in person.
Well, I have yet to see her up close and personal, but Demetria Kalodimos is on local TV news every night and her eyes are as dominant a feature for her as any in that linked thread. It’s like her irises are bigger than her eyeballs.
In answer to your query, I would assume that the basics are there but a lot of enhancements by makeup, lighting and other tricks are involved in most publicity shots of them. I say that because I have seen candids of most of those people and without all the help they aren’t all that special. Some are scary!
But I feel sorry for you if you don’t see such eyes in person. There are many in these parts. Now and then I will have to beg someone’s pardon for staring at their eyes. The best trick is to wear shades so you can stare all you want. 
Eh. I’ve been told I have large expressive eyes, in person and without makeup. So take that as you will. Some people have big eye genes, some don’t. Not everything is faked.
I once met a woman whose eyes gleamed back at me. I mean, shiny. I really dug her eyes. Too bad she was 10 years older, happily married, and in a work setting, 'cause I really dug her. And not just her eyes, but yes, if I could ever find another woman with eyes like that I’d marry her in a heartbeat. Or pay her to stare at me, or something.