Apple and Google developed a joint venture API for COVID19 tracing, very similar to Sweden's DP-3T model.
They are rolling it out to phones. However, that API/setting on your phone only allows for other apps to utilize it. As of today (July 10th) that setting doesn't do anything to alert you if you are in proximity to another user with a confirmed diagnosis.
I'm a software engineer and literally just spent the last few days reading about these models and how they work. If anyone has questions feel free to ask.

