Oh, chocolate brown leather is extremely versatile, so you should have many, many choices of wall colors that would work. What colors or fabrics are in the rest of the room (rug, for example)? Are you interested in a warm, cozy, darker feel to the room or do you want to lighten the effect of the leather? Are you generally attracted to modern or traditional styles?
If you do a search (link below) on Houzz for photos of rooms with brown leather sofas you'll see the wide range of possibilities:
https://www.houzz.com/products/brown-leather-sofas-prbr2-br~t_524~a_88-3--623-12953

yes, look through photos on houzz and start to get a feel for what you like and are drawn too. If you are adding anything else to the room, like artwork or a patterned fabric, thats where you should get your color palette from. The other thing I tell clients to ask themselves is what is their favorite season. the four seasons have different colors that people associate with and if you love fall then you will be naturally drawn to those warm colors such as golds, oranges, terracottas.... But honestly brown is very neutral and you will be hard pressed to find a color that doesn't go with it.

I agree, most colors work with brown leather sofa, depending on its style, from more traditional to contemporary.

Thanks for advice! Its a small space that i'd like to lighten.

how about lime-ish green?