How many words do you have in your physical appearance vocabulary? You may not need too many details to describe characters in your story, but it’s imperative to convey their physical features enough that your readers or listeners can envision and engage them.
A protagonist in a Japanese book I read in junior high school had distinctive eyes—Sanpaku (three white) eyes, which are the eyes with visible white between the iris and the lower eyelid. (Does English have such an expression?) Personally, I’ve never noticed anybody with Sanpaku eyes except for cats, but the imagery was so vivid that I could picture her eyes every time she appeared in the story.

Now, let’s see how we can describe eyes. It’s a tiny area, but when we think of the entire eye, there are so many ways to describe them and it can be impactful because the eyes are the windows to the soul.
Are the eyebrows rounded, soft angled, hard angled, flat, s-shaped, or straight? What about the shape of eyes? Almond, hooded, or downturned? What about eyelids, color of eyes, shape of eyeballs?

If all the characters look similar in your stories, you may want to explore other options.