Hi,
This requires being a little familiar with two things in Unity:
UI RectTransforms and
Animation.
Briefly, here are the steps:
1. Set the pivot point of the cartoon bubble panel's RectTransform to the point of its tail (i.e., at the bottom).
2. Inspect the panel that you want to animate. If you want the cartoon bubble to pop open at the beginning of the conversation, inspect the Dialogue Panel. If you want it to pop open with every line that the NPC speaks, inspect the NPC Subtitle Panel. If you're using the NPC Subtitle Panel, expand its Animation Transitions section. Set the Show field to "Show" and the Hide field to "Hide".
3. Make sure the panel has an Animator component. Create a new AnimatorController and assign it to the Animator. You can make a copy the SF Unity UI Dialogue UI's AnimatorController. This makes it easier because it's already set up; you will only need to assign different animation clips to the states.
4. Then open the
Animation window. Create a new animation clip, maybe called "PopOpen". Add a key for the bubble panel's Scale. At keyframe 0, set the scale to (0,0,0). At a later keyframe (e.g., 0:10), set the scale to (1,1,1).
5. Finally, add/replace the animation clips in your AnimatorController.
When you play your scene, keep the Animat
or window open, and inspect the bubble panel. This will show the panel's current animation state. When you start a conversation, it should transition to the Show state.