Xcode 12.0 Beta 6 was released on 25 Aug 2020 and requires macOS 10.15.4+.
It can be downloaded from https://download.developer.apple.com/Developer_Tools/Xcode_12_beta_6/Xcode_12_beta_6.xip.
Release notes are located at https://developer.apple.com/documentation/xcode-release-notes/xcode-12-beta-release-notes.
The SDKs it contains are:
- iOS 14.0 (Build 18A5357e)
- macOS 11.0 (Build 20A5354g)
- tvOS 14.0 (Build 18J5370e)
- watchOS 7.0 (Build 18R5368d)
The compilers it contains are:
- clang 12.0.0 (Build 1200.0.31.1)
- swift 5.3 (Build 1200.0.28.1)