Trigger animation based on auth user data change?

I have a 'new message' tab that has a conditional view setting that if the 'new_message' boolean is true, it will display the new message widget. Because it's a stream of firebase, I will appear if the value is true and disappear if it's false without anything else needing to trigger it.
What I'd like to do is trigger the animation of the widget instead of it just popping up visible. The animation is set to hide and off screen until triggered where it slides in and waits 2 seconds and slides out.
Any ideas on achieving this? I'm familiar with custom code if I need to add an action, but not sure how to trigger the action to trigger the animation.
Thanks in advance!