What would be a permanent solution for under eye hollowness and Dennie-Morgan folds?

In order to have long lasting change, this requires canthoplasty with possible lower eyelid retraction surgery. Your eyebrows are fine but you are lifting them the tail in the desired photo. It is best to have personal evaluation to determine what is possible and realistic and safe.

I agree with Dr. Steinsapir. The prostaglandin analogue class of medication has been shown to have periorbital atrophy as a side effect. Studies have shown return of lost volume with cessation of the medication (this could take months). Best to stop it now and see how much volume returns...

Unfortunately, the short answer  to your question is no. That is a fixed feature dependent on your bony anatomy. Your photo does show mild ptosis which can make the eyes a bit more open and alert. Seek a well trained Oculofacial Plastic Surgeon (Oculoplastics)

Lateral canthal surgery alone will not achieve your goal. You also have ptosis or heavy upper eyelids. These issues can be addressed together. This will allow the eyebrows to relax a bit. It will move your look in the direction of these handsome models. Will you have the magical looks that allow...

Agree that these are NOT festoons. You would be a good candidate for filler to address the volume deficiency. You would also be a good candidate for skin resurfacing to address pigmentation and texture changes. I recommend you see an eyelid or facial expert in your area to address...

If you live in a major American city, likely in your community there is a University based Oculofacial surgeon who provides the bulk of this care. In the largest cities there are specialist in private practice who also offer these services. There is a new drug approved to control active thyroid...