I had eczema since I was a baby and I was lighter now I'm dark but my face is lighter than my bod. Do eczema make your skin darker?

It can. Following skin inflammation the skin may either appear bleached or darken. This occurs where the rash had been previously.
It's possible. Anything that irritates or causes breaks in the skin surface can cause the skin to heal lighter or darker than unaffected skin. If you keep your eczema under good control, over time the affected skin will gradually get closer in color to the rest of your skin, although it may not ever be an exact match.