Hiya.
I had jaw recontouring about 2 weeks ago in the uk and am now age 30. I started HRT and transitioned in 2002 if that's relevant I don't know, but my skin is I'm very good condition. I am finding there is no sagging at all, as the swelling goes down, my skin is snapping back in place, and my cheekbones are now more prominent already.
At 26 I very much doubt you will have any issues. 🙂