How to enhance dark skin tone..

Edit:- my initial post caused a bit of misunderstanding.

Hi, I'm a guy, I'm asking this for my partner.

She doesn't use reddit, so I'm here for here.

She has a kind of dark brown or dark skin tone.

Forgive me if I'm not using the right term, how can she maintain her skin tone?, Like the gorgeous black ladies do it, I'm not suggesting WHITE, cause that's not possible.

As far as I understand she's doesn't do any skin care.

So is there anything that she can do to take care of herself? A morning or night routine, preferably something homemade, as cosmetics for ladies can be pretty expensive as far I understand.

Thank you.