There is a third party software product that does exactly that, and I used it before a few times (Reincubate Camo; originally saw it in mentioned in HN comments

There is a third party software product that does exactly that, and I used it before a few times (Reincubate Camo; originally saw it in mentioned in HN comments, actually). Great results, and works cross-platform (tested myself on win10 and macos), but it comes with limitations and is paid through subscription (outside of the basic tier with plenty of restrictions). The UX is also a bit annoying, and it requires a USB cable. If Apple manages to integrate this functionality well as a first party macOS tool, and makes it seamless, it will be a great and welcome feature, imo. People underestimate how shitty laptop webcams are compared to any flagship smartphone camera from at least the past few years (if not earlier). People were consistently blown away by my results with the third party tool I've mentioned, so a lot of people would imo be pleasantly surprised by how awesome the results could be with the native one.