What's the lowest Mac OS version that can run XCode
Xcode and Mac OS versions compatibility
The Xcode Support page includes a table with several recent Xcode versions and details about what that version supports. Please see the Minimum OS Required column to answer your question.
Which Xcode ? 12 up to 12.2 ?
It is macOS 10.15.4+
There is also a very detailed information here:
https ://xcodereleases .com
It is macOS 10.15.4+
There is also a very detailed information here:
https ://xcodereleases .com