My skin tone has become particularly dull and rough. How should I manage whitening and tone-up?

As autumn approaches, far from returning to its original state after the tanning of the summer, my complexion looks dark and dull, almost earthy, perhaps due to a slowed metabolism causing the stratum corneum to thicken. The freckles and blemishes that deepened in patches from the strong summer UV rays also stand out particularly more due to the dry weather, which is a major concern. Although I make sure to apply whitening essences and Vitamin C ampoules, they seem to just sit on the surface—perhaps due to poor absorption—and I find it difficult to feel any noticeable tone-up effect. I would appreciate any skincare tips to restore a clear and radiant complexion without straining the skin during this dry and sensitive transitional season of late autumn. Additionally, if there are any recommendations for pigmentation and whitening treatments like Pico Toning or Iontoson, please let me know.