It depends what you mean by firming. If you just have subtle softening and you are in your 30's, you might be a good candidate for a skin tightening like thermage that stimulates collagen and gives a mild tightening effect.
However, if you are 45 and up and experiencing laxity of the chin with jowl formation and pockets of the skin that are starting to hang, then the gold standard of that is a facelift.
A facelift is just for the lower face, the mouth, and jawline area. You can also do a neck lift at the same time as a facelift.
How do I know if I'm a candidate for a neck lift or skin tightening?
Consult with a facial specialist who does both of these treatments so you know you're getting an unbiased opinion.
Make sure the doctor you consult with gives you a realistic expectation of what these procedures will do for you. Anything non-surgical will always just create a subtle improvement over a course of treatments. Only subtle time but no downtime.
If you are looking for significant results, you do need to have surgery.