Some games are notorious for refusing exclusive fullscreen on Windows 11 without Dxcpl. Here is a "Hall of Fame" for the dxcpl fix:

Technically known as the DirectX Control Panel, dxcpl.exe was a utility included with the DirectX SDK (Software Development Kit). It allowed developers and advanced users to override DirectX settings for specific applications.

Its most popular use cases included:

Let’s walk through a typical dxcpl Windows 11 exclusive configuration to force an old game (e.g., The Witcher 2) to run smoothly.

If you are looking for dxcpl.exe natively installed on a fresh Windows 11 machine, you will not find it. It is not a standard part of the consumer Windows 11 installation package.

Why is it missing? Windows 11 comes pre-installed with DirectX 12 (and support for DirectX 12 Ultimate). Microsoft has shifted its architecture. The old "DirectX Control Panel" was designed for the DirectX 9 through 11 eras. With the introduction of the Universal Windows Platform (UWP) and modern DXGI (DirectX Graphics Infrastructure), the granular controls found in the old dxcpl have been rendered largely obsolete or moved elsewhere.