Samsung has started the One UI 3 and Android 11 beta program for the Galaxy S10 series (via SamMobile). The company has already been running the One UI 3.0 beta program for the Galaxy S20 and Note20 series for the last few weeks. It had also launched the beta program for the Galaxy Z Flip but had to pull the initial firmware due to high battery drain issues.
For now, Samsung has launched the One UI 3 beta program for the Galaxy S10e, Galaxy S10, and Galaxy S10+ in India, South Korea, and the United Kingdom, though there's a possibility that the program is expanded to more regions within the next day or two.
You can check if the One UI 3 beta program for the Galaxy S10 series is available in your region or not and then join the program using the Samsung Members app.
Samsung has been aggressively rolling out One UI 3 beta firmware builds for the Galaxy S20 and Note20 series signaling that a stable rollout is around the corner. For the Galaxy S10 series, the One UI 3 update is expected to hit the stable channel by the end of this year or early next year.
One UI 3 is based on Android 11 and comes with a number of UI changes including a streamlined Settings menu, updated Phone app, revamped notification shade, and more. You can read more about One UI 3 features here.