My eyebrows (especially lateral parts) have dropped after blepharoplasty, ptosis repair. Will this improve?

Your brow position might improve slightly as you heal. However, you correctly assessed that your brows have dropped because you no longer need to compensate for the heavy lids and eyelid droop. If your brows continue to trouble you they can be lifted once you've healed from your blepharoplasty - typically 3-6 months. I hope this information is helpful for you.Stephen Weber MD, FACSDenver Facial Plastic Surgeon

It is unlikely for the eyebrow to go up by themselves. You are correct as to why have fallen.  Lateral brow lift can be considered at this point. See link below.

You are correct that the brow can drop after the eyelids are lifted. When you have a ptosis the brow works harder to help elevate the lids.  When the lids are lifted surgically, the brow can relax, and may fall.  At this point you still have some edema which can also pull the brow down.  So wait for this to resolve.  If the brow is still low, you can do some Botox to elevate it, or do a surgery to lift the lateral brow.