Can knee braces straighten bowed legs in adults?

Not likley. Either you are genetically destined to be bow legged or increasing wear along the inside of the knee with time is causing you to become bow-legged. Rarely a disease process could contibute to bowing of the legs. See an orthopedist for clarity in diagnosis. Unloader braces can be helpful with pain and function but cannot straighten an adult bowed knee.