There are a few options available when it comes to firming up a sagging neck, often dubbed “turkey” neck. Non-surgical options like Botox treatments can have some effect if there are bands that form when you form facial expressions.
Minimally invasive treatments such as liposuction can also be a potential treatment option if your skin is overall pretty tight and the issue is just extra fat. The best recourse is to seek a face to face consult with a surgeon skilled in neck lift treatments. I’d recommend asking for before and after photos of past similar cases and come prepped with a list of questions to ask.
With a consult the doctor can assess whether the sagging stems from excess skin or excess fat, etc and then discuss the most viable treatment options for your particular case. Should the sagging be severe a traditional neck lift may be the only direction to go for optimal results. If the sagging is medium to minor, the doctor can then lay out any potential alternate treatment actions and help you make the best decision possible.