In Android 11, you'll now see that notification settings and per contact notification settings are now all managed via Android Settings (i.e. no longer managed directly in the Textra SMS user interface). 

You can still access these Android Settings via Textra SMS using the Android Settings button or via Android Settings > Apps and notifications > Textra SMS > Notifications or long pressing on an incoming message notification. 

Unfortunately, there is no Textra heads-up style anymore, it is not compatible with Android 11 Chat Style notifications. In addition, the Android Settings user interface may or may not provide the LED color option (phone specific) or the vibration pattern (phone specific).

To turn on Android 11 Chat Bubbles for a given chat, tap the icon (bottom right) on an incoming message notification (looks like a square with an arrow in it). To turn off chat bubbles, go to that chat setting (via Textra SMS, Android or the Notification) and turn off 'Bubble this chat'.