Global settings for vibrate patterns on AOSP and Pixel have been removed in newer android versions. Chomp SMS has an app specific call for vibrate patterns on notifications, and has a custom option that allows users to input the length of time in seconds for vibrations and paused (e.g., 0.12,0.1,0.12 would be two short vibrations with a slight pause in between). Would very much like to see this in Textra.