4 weeks post op Chin Implant, I can't close my lips and my lower lip is stiff. Is this normal? (photos)

Thank you for your pictures.  I believe your chin implant is too big. It is causing you mental is muscle strain which makes it difficult to achieve lip closure. I particularly like a woman to have a softer chin on profile view. Your preoperative profile view appears to be very very good. I would definitely speak to your surgeon about at least resizing your chin implant to give you a little softer profile and less lower lip/mentalis muscle strain.

Appears as very expected healing phase as your are describing. Best to have very close follow up with your surgeon as needed.