I predict shrinking would not be too difficult to add. Shrinking could also fit in with story/worldbuilding I have. I'd like to do a few detailed interiors that could serve as levels for shrinking, but making growth mechanics, NPC interactions, and levels for larger sizes will be higher priority for now. After growth part of the game is in good state, I may do something with shrinking, if there is still interest; I have a few ideas for that.
I'd like to make player being able to outgrow buildings from inside, if that's what you meant by "burst out". Though, it would likely not deal damage.