Can Botox address an upper lip sneer? (Photos)

Yes, Botox may be able to improve this. You'll want to see someone meticulous. It will take 1-2 weeks for final results. I recommend getting a formal evaluation with cosmetic dermatologist. Best, Dr. Emer

Thank you for sharing your question and photographs.  This appearance is likely due to your cleft lip, depending on how significant the microform was.  That said you may be able to improve upon your resting posture with a small amount of botox into the more active side through a trial and error process.  See an ASPS board certified plastic surgeon to assess the best dosing and location.