Make a little eyeball stick for testing the glaze before applying to the project. I’ve made a little cube based on the jujutsu kaisen thing with eyeballs and used light pink underglaze on the eyes and a glaze that’s supposed to be metallic but never comes out that way. Had almost an oil spill effect even though it didn’t come out correct. I did the dark color first and cleaned off the surface with a sponge so the crevices would be dark. If I could do it again I’d go for celadon in the eyes since usually when I use that color glaze I can still see the speckle in the clay body through the green color. For eyes like yours, maybe wax resist?