You can't typically track someone from their app in real time. They have to upload a ride or other event over wifi, bluetooth, or other methods to Strava. Many athletes use settings for automatic uploads when they finish a ride. One can also send alerts to friends when starting a ride, abrupt stops (accident alerts) etc. But these settings are easily turned off. Although you can record events directly with Strava on a phone, most people record directly with a GPS device (watch, bike computer, etc.) then transfer the info to Strava.
KA undoubtedly had a watch or other device. MW's settings were probably for auto uploading. Her and CS's Strava accounts are locked now, but a a screen shot from an earlier MSM reposrt from MW's Strava home page showed she had just done a PR on a segment called "Chipseal Rollercoaster" which is just outside of Austin. Most pros, like MW and CS, would use on bike computer GPS units that track power, heart rate, etc. KA may have used one of these too, or just a watch.
Not sure this has come up before, but KA is a pretty capable cyclist. She finished in the middle of the pack at the Steamboat Springs Gravel Race in August 2021 (
https://www.athlinks.com/event/300676/results/Event/982822/Course/2111404/Bib/33?source=internal). CS finished 7th, with former World Tour cyclist, Alex Howes, winning. MW doesn't seem to have been there. At these events there's usually a handful of pros racing for the win and the rest of the field are mostly talented amateurs. KA did the 144 miles in 9:22, a pretty respectable time.