You underestimate the benefits of puberty blockers and hormone therapy on “passing”.

Someone in high school that’s had access to puberty blockers before secondary sexual characteristics become prominent is already going to present fairly androgynous because that’s what puberty does, it extends sexual differentiation.

If the person then also has access to hormonal treatment, they’ll be experiencing what is essentially the exact same development of secondary sexual characteristics as they would if their own body was producing them.

Hormones aren’t going to grow reproductive organs that aren’t there, but when it comes to things like facial hair, hip and shoulder width, breast development, that’s going to be visually congruent with however the person would have progressed had they been born with the endocrine system that matches.

Now, if a trans person progresses into puberty before having access to treatments, then you’ll have an ever increasing degree of body changes congruent with their assigned gender.

So, no, them having eyes isn’t some kind of automatic trans detection system.

Hell, some folks, they don’t have a ton of differentiation even once they’ve completed puberty, so you can have adults that start hormones without any other treatments end up “passing” without any visual cues.