I'm 22 and have creases (rings) around my neck. I'm about 24% body fat. Could this just be extra fat or what?

Without photos to view at this time, it's not easy to determine what may improve your concern. For #creases, you may benefit from #non-surgical treatments. I suggest consulting with a board-certified plastic surgeon to learn about the #options and products available and as to which may be best for you.It's best to begin by consulting with a surgeon in-person. The presence of banding down the front of the #neck, and, amount of excess skin are among some factors which determine what treatments will best rejuvenate your neck. In your case, it sounds as though your banding is across the neck which is not always improved surgically but may be with #non-invasive in-office services.

Fat collection in your neck are multifactorial - for example "runs in the family", related to your weight, hormonal, etc. Liposuction using fine cannulas are very helpful for this. If loose skin is an issue then some non invasive treatments like Ultherapy, Thermage, Thermi-RF, or the Sciton Laser BBL SkinTyte are good options as well

Weight gain can easily be seen in the neck region.   However even thin people have neck creases.   That is where the platysma muscle is thick and has visible creses over thin skin of the neck  These are difficult to remove.   Best to you