OnePlus 9RT went on sale in India on 14th January 2022, launching with OxygenOS 11 out-of-the-box. It was the third device to receive an update to OOS13 back in 2022, first via a Closed Beta on 13th August, followed by an Open Beta on 14th October, and finally, the first stable build on 14th November. OxygenOS 13.1 is not a major update by any means, it's similar to OxygenOS 12 → 12.1.
Anyway, the first 13.1 build for 9RT carries the F.18 version number, displayed as 188.8.131.520. This marks the return to a better versioning format, similar to how it was before the Oppo-merger (e.g. 184.108.40.206, 10.0.1). If you wish to update to 13.1, you can do so via the app itself, since both full & incremental ZIPs are available.
It's also important to note that the Nord CE 3 Lite was technically the first device with 13.1, since it launched with it in the first place. 10 Pro received it 3 weeks ago, 10R got it a week later, and other devices (11, 11R, 9R, etc.) were also updated to 13.1 recently.
Changelog for 220.127.116.110
- Seamless interconnection
- New auto-connect feature enables automatic connection between phones, tablets, and PCs placed in close proximity.
- Expands Omoji's functionality and library.
- Adds a new TalkBack feature that recognizes and announces images in apps and Photos.
- Adds the new Zen Space app, with two modes, Deep Zen and Light Zen, to help you focus on the present.
- Improves Simple mode with a new helper widget and quick tutorials on the Home screen.
- Gaming experience
- Adds the Championship mode to Game Assistant. This mode improves performance while also disabling notifications, calls, and other messages to give you a more immersive gaming experience.
- Adds a music playback control to Game Assistant, so you can listen to and control music easily while gaming.
It's important to note that the new "Seamless interconnection" auto-connect feature (between nearby phones, tablets, PCs) is mentioned in this changelog, even though it was not part of the other changelogs. It was initially in 10 Pro's, although with this note added in later:
Where can I install stable OxygenOS 13.1?
If you're currently on the stable track, you should have already received a notification from the app about this update. Please ensure you've selected either of the stable update methods in the app's settings, since the beta track doesn't receive updates separately from stable anymore (post Oppo-merger). Beta track is now meant only for the first few major Android builds, nothing more. Disable advanced mode as well, in case it's turned on for whatever reason. The stable track will continue to receive updates until the device is marked EOL (End-of-Life).
Once you're on the main screen of the app, simply download the update presented to you and follow the installation guide.