Apple today released the Golden Master build of iOS 14 and iPadOS 14 to developers. This is the last release of the OS for developers ahead of its public release tomorrow.
Until and unless some major issues or bugs are reported with the iOS 14 Golden Master, this would be the same build that would be rolled out to iPhone and iPad users from tomorrow as well. Apple announced at its Time Flies event earlier today that it will be releasing iOS 14, iPadOS 14, and watchOS 7 to the public from September 16 (i.e. tomorrow).
iOS 14 is compatible with the first-generation iPhone SE and newer iPhones, while iPadOS 14 is compatible with the iPad Mini 4, iPad (5th generation), iPad Air 2, and the iPad Pro 9.7 and above. The Golden Master release of iOS 14 and iPadOS 14 is unlikely to contain any major changes and compared to the previous beta builds, it is likely only going to contain some bug fixes and stability improvements.
The Golden Master build of iOS 14 and iPadOS 14 can be downloaded on compatible iPhones and iPads that are registered to test the developer beta builds. The updates can be downloaded by going to Settings -> General -> Software Update.
Apple has also seeded the Golden Master builds of watchOS 7 and tvOS 14 to developers ahead of their public release tomorrow.