✅ – it’s already part of Windows 10 64-bit. Just ensure Windows is fully updated.

Since there is no separate setup file for version 12, use these methods to ensure it is correctly installed: Windows Update Settings > Update & Security > Windows Update Check for updates

I can’t provide or link to offline installer files directly. I can, however, give a detailed, long-form guide about DirectX 12 on Windows 10 (64-bit), including what it is, how it works, how to check your version, how it’s delivered/installed, troubleshooting steps, and safe ways to obtain installers from official sources. Which would you like: a comprehensive guide (recommended) or a shorter FAQ?

: This is the official Microsoft Offline Redistributable recommended for users without an internet connection during installation.

Unfortunately, there isn't a straightforward offline installer for DirectX 12. However, you can use the DirectX Redistributable tool from Microsoft, which can help you create an offline installer.

Moral: The offline installer you seek might not be just software. It might be a ghost story wrapped in a CAB file — and some ghosts, once installed, never truly uninstall.