Xcode 12.5 includes SDKs for iOS 14.5, iPadOS 14.5, tvOS 14.5, watchOS 7.4, and macOS Big Sur 11.3. The Xcode 12.5 release supports on-device debugging for iOS 9 and later, tvOS 9 and later, and watchOS 2 and later. Xcode 12.5 requires a Mac running macOS Big Sur 11 or later.
Full details are in Apple’s release notes.