Depending on the cause of the darkness under the eyes, it can lessen the visual appearance of dark circles.
When we age, we lose bone, fat pad and muscle. The fat pads start shrinking in size and declining down the face, the muscle weakens and bone structures change from bone reabsorption. The malar fat pad under the eye starts to descend down the face, showing separation of the obicualris retaining ligament. This ligament is what separates the lid-cheek junction. If there is a visable deficit (dark circle) from bone reabsorption and separation of the fat pads, adding dermal filler to replace lost volume will definitely lessen the appearance of dark circles.
Other reasons for dark circles include pigmentation and visible vascular structures, as the skin around the eyes is the thinnest skin on the entire body. Dermal filler will not help with the appearance, if these are the cause. Other means of treatment may be laser treatments, such as IPL and skin needling.
Dr. Jonathan Brown from City Skin Melbourne does a great video explaining dark circles and dermal fillers here: https://cityskin.com.au/dermal-fillers/under-eye-bags-tear-trough-treatment/