It’s difficult to gauge the depth of it, as it looks like the base is also red (which can give an illusion of being even deeper than it actually is). Time will help, though there are topical options to speed up fading of post-acne dark marks, including azelaic acid and hydroquinone. IPL (non-ablative laser) can also help with this. You may find that it is much less noticeable when the darkness fades.

If on the other hand it is actually deep as well as dark (or still looks very noticeable even when the darkness has faded) - I’m afraid this is a pretty big scar. Multiple sessions of micro needling may help soften the edges and raise it up a bit, but realistically with a scar of this size, surgical revision may be your best bet (cut out the existing scar and replace it with a thin, flat, linear one that is less noticeable over time). I’d make an appointment with a dermatological surgeon if I were you.

Hope that helps. :)