If you have already tried FUE, then what remains is either a re-excision with trichophytic closure to allow hair to grow through the scar, and possibly scalp micropigmentation. Fraxel and C02 laser will likely not help much.
Scar reision for strip hair transplants
There are many ways to improve the scar of a strip procedure. You have already tried the FUE which brings hair to the scar and minimizes the contrast of the neighboring areas with the scar. Scar revision with a more aggressive trichophytic closure can produce a good results in most cases. That is especially important when there is a healing problem or in case the scar is either elevated or depressed due to initial closure problems. There are a variety of laser skin resurfacing techniques that are useful for the other smaller scars like facial acne scar but may not be a great option for surgical scars like what we have after hair transplant.
The best is to find a good hair transplant surgeon with plenty of experience in scalp scar revision.
The reason you see your strip scar is because there is no hair there. Softening it with lasers / Fraxel/ or dermabrasion will
The reason you see your strip scar is because there is no hair there. Softening it with lasers / Fraxel/ or dermabrasion will not work. You can consider SMP to hide the scars. See VIDEO above.
it is best to see a hair restoration specialist to get an evaluation and find what is best in your situation.
You are implying that your strip scar is elevated and whitish in color. Strip scars that are elevated are best treated with intraluminal steroids and the color can easily be brought up to normal with scalp micropigmentation (see example of such a scar in the web reference below). This example is a typical example of our work and despite what you see, the scar is still there.
I would recommend placing more fue grafts into the scar. You can consider non ablative fractional laser treatments (1540nm laser)that help scar appearance and might even stimulate hair growth. Scalp micropigmentation is also a consideration.