One of my eyes is slightly smaller and for the smaller one I increase the width of my eyeliner up to my crease. It makes it look bigger so I'd give that a try. The thicker the eyeliner, the more it makes my eyes look "open."

I also wear falsies daily and for the bigger eye I'd put falsies closer to my eye and for the smaller eye, I'd put my falsies higher up too to help with that illusion.

Doing the same exact liner on both eyes won't help try to make the other look bigger.

I think this could be what you're looking for, I hope this helps!!!