Would dermapen be more effective at tightening loose skin rather than a radio-frequency treatment?

Microneedling doesn't tighten skin. I combine needling with lasers and RF treatments or ultrasound to get the best outcomes.  Dr. Emer.

Microneedling is a wonderful treatment that helps with skin texture, tone, fine lines, and scarring. However, it does not do much for skin tightening. If your main concern is skin tightening, I would recommend doing a radiofrequency-based treatment.I hope this answer is helpful! Best of luck.