On Windows 11, new computers start shipping with a dedicated button to get quick access to Copilot. However, since this is a physical addition to the keyboard, the existing devices won't have a dedicated physical option to access the chatbot.
Of course, you can use the "Windows key + C" keyboard shortcut or the Taskbar button to open the chatbot interface. Microsoft is even trying to open the Copilot panel automatically on devices with monitors equal to or larger than 27 inches. However, if you want to open Copilot on the desktop with a dedicated key, it's still possible to do this by remapping any key on the keyboard to the Copilot shortcut.
