OxygenOS 13.1 is the latest version of the OxygenOS operating system, developed by OnePlus. 

It is based on Android 13 and was released in February 2023. 

OxygenOS 13.1 brings a number of new features and improvements, including: 

A new design language called Aquamorphic Design, which is inspired by the flow of water. 

A new Always-on Display with new clock styles and information. 

A new Zen Mode with new features and customization options. 

A new Game Assistant with new features to improve gaming performance. 

A number of bug fixes and performance improvements. 

OxygenOS 13.1 is available for a number of OnePlus devices, including the OnePlus 10 Pro, OnePlus 9 Pro, OnePlus 9, and OnePlus 8 Pro and More.

To update your device to OxygenOS 13.1, go to Settings > System > System updates.