I am concerned about fat under my chin and would like to know the name and side effects of the procedure to get rid of a double chin.

My face is losing elasticity overall, and the skin under my chin is sagging like a bulldog's. I've noticed many acquaintances in my neighborhood visiting dermatologists lately to get their double chins removed, so I'm looking into getting the same treatment. However, I know absolutely nothing about this area. If there is a procedure for my age that can cleanly remove a double chin without causing skin sagging, could you please let me know the name of the treatment? Also, given my age, I am most worried about side effects. I would like to know in detail in advance about potential side effects that could occur after the procedure, such as prolonged bruising or skin indentation. I am seeking the wisdom of those who have experienced this.