i heard that your eyes always stay the same size, but i'm skeptical of that. Is it true?

Answer 1

No.

A newborn's eye is around 18mm in axial diameter (front-back), and it grows to about 24-25mm in adults.
However, this is *much* less growth than the rest of the body undergoes.

Answer 2

Here's a related interesting thing about eye size.

Dogs have decended from wolves and have been bred to be very different sizes, from very small to huge. But, their eyes are all the same size regardless of the dog size.

Answer 3

Yes,
I used to have big eyes as a child but now they look quite normal