Please recommend an effective body lifting treatment!

I am seriously considering body lifting treatment as I am concerned about my skin elasticity decreasing significantly after dieting.

I felt that exercise alone had its limits in getting rid of sagging skin.

I especially want to smooth out the lines around my arms and abdomen, and I would like to know which body lifting program is right for me.

I would like to know the specific principles of how ultrasound, which is less painful and does not interfere with daily life, or high frequency, which increases elasticity, are effective.

also,
Could you please explain if there is a separate combination of body lifting treatments recommended based on an individual's body type or skin thickness?
I want to start body lifting treatment because I want to feel more confident when wearing revealing clothes.