Your characters isn’t just what colour their hair and eyes are but overwhelming your reader by going too deep into details is not a good idea.
Your character has defining features and it’s up to you to use it.
If your character is pale, has blue eyes, brown hair, wide shoulders, frown lines , rough hands and so on you decide which features are most important.
Three features are enough to describe a character.
You should always use hair colour as a feature.
It is very simple you describe a regular feature (hair), a feature that adds depth ( eye, rough hands, well muscled, etc.), and a feature that will be remembered ( scars, birth mark, missing limbs ect.) , and then you keep reminding the reader of these three things.
You can remind a reader by simply saying something like “Carter ran her fingers through her blood red hair an expression of worry on her face.”
Or “Argor stood up straight and immediately the lord before him regretted having this man mountain as an enemy.”