What can I do to treat these lines on decollete? (Photo)

The use of a HA skinboosters or HA biomodulators can help to improve the overall skin quality (hydration, tautness and smoothness) in the decolletage area. For further improvement, professionally performed microneedling (no need for the added expense and risks of RF microneedling) may be subsequently or concomitantly performed for additonal improvement in the texture of the skin. You would be wise to consult with a board certified cosmetic dermatologist and be wary when hawked the latest expensive fraxel laser or RF treatments, as the hard science for these "bells and whistles" lags woefully behind the heavy marketing hype and social media buzz that promotes them. Hope this helps and best of luck.