Yes, this is possible. In principle, the iris is a device similar to the diaphragm in a camera.
It narrows and dilates the pupil by regulating the amount of light reaching the retina. In bright light, the pupil becomes narrower, in weak light - wider. In addition, a smaller aperture value is required for the eye when it is necessary to focus on near objects, such as reading a book. The muscles control the iris, so they stretch and compress the tissues of the iris. Because of this, its optical properties change and the iris noticeably changes its color.
Since with some strong emotions (pleasant and not so) the pupils involuntarily narrow or dilate, we can observe a change in eye color in this case. The established eye color of an adult can change with age, but not so quickly, of course. Often the color of the iris darkens or, conversely, turns from dark brown to hazel. Sometimes a change in the color of the iris can be a symptom of an eye disease, such as pigmentary glaucoma.