How does the Warp terminal Mac app achieve this feature that lets users adjust the amount of transparency and blurriness of the window?

I have tried working with NSVisualEffectView.blendingMode and NSVisualEffectView.material, which does get me the blurry background effect but does not let me adjust how blurry it should be.

Would be nice to have a boolean value from 0.0 to 1.0 which adjusts the blurriness — how can this be achieved? Please see the image for context of how the feature works in the Warp app.
Image of Warp app