All leather products can NOT be washed in any case. If one part of leather harness got dirty (Make Up, deo, perfume, glitter etc.), so you can apply a little bit of body cream without perfume, oil and alcohol on the top of the leather and gently wipe with a dry cloth or cotton pads without to pull the leather.
Leather fringe accessories should hang on a hanger. If a part (a part from soft leather) is wrinkled, you can even iron from the leather inside with a dry cloth slight to medium heat (with pressure without pulling the leather).
If the purchased item has a too long harness, you can cut the belt, depending on the personal size.
Keep leather accessories in dark room by normal temperature.