The code has been available to download and compile for a little while, but now Microsoft has released a ready-made Windows Terminal app for anyone to try out.
You can access the traditional cmd line, PowerShell, and the Windows Subsystem for Linux (WSL), all at one place, through the new Windows Terminal. Furthermore, it supports themes and more customization for developers who want to tweak the Terminal app.
Windows Terminal app on Windows 10.
"This very early preview release includes many usability issues, most notably the lack of support for assistive technology", the program's download page says". In the meantime, you can check out the early preview version from the Microsoft Store here.
Consequently, many new features like themes and customization are still very unstable. "Windows Terminal 1.0 will arrive in the Microsoft Store this winter!"