To open the settings, you can either hit ctrl+, (Windows), or go to the dropdown-arrow in the navigation bar and select settings. You can see through the terminal window to the underlying windows and areas-much to like here. Here's what it looks like with the full transparency enabled. Unfortunately, this only works on Windows 11.
Update 2022: Version 1.12 or later of Windows Terminal now supports FULL unblurred transparency.
Here's a list of the posts in this series. Here is another post about fun and helpful Windows Terminal tips and tricks in the series. 💡 TIP: Check out the guidance for building sustainable Azure workloads! 🌿