No, WindowBlinds does not enable you to tweak parts of the default Windows theme. You can apply a WindowBlinds theme (and make some changes to it if you like), or you can use the default Windows theme (which means that you have unloaded WindowBlinds.)
That being said, there is a wide range of WindowBlinds themes available, ranging from the very minimalist to the very extravagant. You can download a 30 day trial of WindowBlinds if you like:
https://www.stardock.com/products/windowblinds/download
(I had a little trouble getting the "Try it Free" button to work just now for some reason, had to use the browser "Open in a New Tab" option to work through to the download.)