Several trans friends have told me, that their eyes got bigger due to HRT... I didn't believe it that much, until my mother said to me one day: "Wow, your eyes had become so much bigger and expressive!" Later, many friends told me the same, so I assume it is true

As far as I remember, my eyes were not exactly smaller, than now, but maybe more closed and eyebrows were a little bit lower, which gives the look of smaller eyes.
Also, I've noticed, that my eye movements became much more intense and wider in every direction, which may caused overall changes in the appearance, because it acts like an eye-fitness

and therefore leads to changes.