Yes it can. That's how you know it's real. The more you use real leather the darker it can become. People like Louis Vuitton and other high end leather goods makers call this natural darkening process the "patina" and it's a way for experts to judge the age of a leather piece and it's how we authenticate real leather from fake leather. Brown leather can oxidize if it was colored with dyes made with tannins. It can also turn darker from contact with the oil and sweat from your skin when you touch it. It can turn darker from dirt and use. When you combine all the above then it's obvious that leather does darken with age and usage. And if it's a color you hate it can turn darker when you use a highly pigmented polish or a liquid leather dye. Go to a shoe repair place and ask if they have any high dye or high pigment products that will change your wallet to a color that you like.
no
No, it will go lighter, the only way it will go darker is if you pop some leather polish on it
