It depends on the technique and incisions used. A crescent shaped excision is not likely to produce significant tightening in the posterior thighs. However a longitudinal incision is more likely to provide overall better correction albeit with a longer more visible scar.
A medial thigh lift (excision in the bikini area) will not tighten posterior thigh skin. A thigh reduction ( vertical scar) can thighten posterior thigh skin. However the scar is long and wide and is visible.