Can acne scar treatment bring about changes even to old scars that are several years old?

My scars aren't recent; they're almost a few years old, so I keep hesitating whether starting acne scar treatment would even be worthwhile. At first, I thought they would naturally fade over time, but even though the redness and brown marks have faded somewhat, the sunken look of my skin remains.

It looks fine, especially in bright lighting, but when light comes in from the side, shadows form and it suddenly looks much worse.

So, I would like to start treating my acne scars now, but I am wondering if old scars tend to change more slowly than newer ones.

Since it has been the same for several years, I don't expect it to improve dramatically after just one or two treatments, haha. However, if there is even a slight possibility that my skin texture will become smoother than it is now, I plan to take my time and continue doing it consistently.

During the acne scar treatment consultation, do they ask when the scars formed or how severe the acne was in the past? I have photos from when my skin was at its worst, so I am thinking of bringing them to the consultation.

Also, even with old scars, it seems the reaction might vary depending on their depth and shape. Is it actually possible for some parts of the same person's skin to improve quickly while others show little change?

I don't expect all the scars to disappear equally; I think I would be satisfied if at least the deepest-looking parts became a little softer.

For those of you who started acne scar treatment because of old scars, did you notice a difference compared to your before photos after a few months?

Are there any people who thought it wasn't a big deal at first, but saw a difference when comparing photos after receiving it several times?

It's a scar from a few years ago, so I was thinking of just giving up, but it keeps bothering me. I really want to hear realistic reviews from people who started in a similar condition.