Deep malar grooves at 18. Would I benefit from fat grafting?

Unfortunately without photos this may be just a suggestion. Many young people born with small cheek bones demonstrate malar groove deformity (tear trough) early in the childhood. Correction can be achieved with malar augmentation using cheek implants. A transconjuctival lower blepharoplasty is usually done in the same time. Hope this helps.

Without seeing pictures, we can’t begin to make an assessment.
It’s not appropriate to give you a recommendation in regards to having a procedure, but considering your age I would stay on the side of caution.
Any attempt at making your face look better can also create the opposite.
Best,
Matt Hagstrom, MD