Apple yesterday released the Golden Master versions of iOS 14 and iPadOS 14 updates to developers. This is the last release for developers before the release of the public versions today.
If no serious bugs are found in the Golden Master version, then this particular version will become public. Apple announced that it will release iOS 14, iPadOS 14, and watchOS 7 publicly today (September 16).
iOS 14 supports iPhone SE 1st generation and later, and iPadOS 14 supports iPad Mini 4, iPad (5th generation), iPad Air 2, iPad Pro 9.7 and later. It is unlikely that the Golden Master versions contain any changes compared to the previous beta versions. Most likely, they only contain bug fixes and stability improvements.
IOS 14 and iPadOS 14 Golden Master versions can be downloaded now with a developer account. This is done as usual via Settings> General> Software Update.
Apple has also released watchOS 7 and tvOS 14 Golden Master versions ahead of the public release today.