Check the docs for BaseItem.getProperty: “Gets a custom property from this object.”. It’s talking about CoSpace Properties, which are global variables you can create and access across scenes and scripts.
All object properties are accessible via standard JS dot notation, so:
let rabbit = Scene.getItem("nK7SXb3X") as AnimatedItem;
Debug.log(rabbit.opacity));
Hope that helps! Let me know if you have further queries about this. If this post solves your problem, please mark it as the Solution.