As the others have noted, covering it with some sort of tape is the easiest & least expensive option available.
Technically it is possible to remove the Bezel portion and install a replacement bezel, but Apple and most AASPs will not do this since the official Apple repair involves replacing the entire Display Assembly which is very expensive (easily $500+ US). Replacing this Bezel is not without risk since it is very easy even for an experienced hardware tech to damage one of many very fragile & delicate cables located beneath the Bezel. I have replaced hundreds of these Bezels on my organizations 2016+ USB-C Apple laptops....a few times I have damaged one of those cables and I have lots of hands on experience. It is also a bit tricky to properly fit the replacement Bezel since there is very little room for error...only one chance since adhesive sticks really hard).
Oh, and cosmetic repairs will cost the same as any other repair and may even be considered accidental damage (for a mail-in repair, that would increase an already expensive repair).