watchOS 26 will be compatible with the same models as the current Apple Watch software, according to a claimed device compatibility list.
If your Apple Watch is running watchOS 11, it should be able to update to watchOS 26 when it's released to the public in the fall.
The rumored device compatibility list for watchOS 26 includes models from Apple Watch Series 6 onwards, such as Apple Watch Series 7, 8, 9, and 10, along with Apple Watch SE and Apple Watch Ultra variations.
watchOS 26 is expected to bring a revamped user interface, new watch faces, customizable Control Center, and Apple Intelligence features like AI-powered notifications, Siri enhancements, and Genmoji creation.