I'm Chris and I write CGA rules at Esri! I'm going to share some rules here on GeoNet occasionally. Here is one that does 3D Text. Download it, use it, change it... whatever you'd like! The rule is pretty easy to understand. It uses pre-modeled assets for the letters. This one is roughly like the Arial font. It uses a semi-colon as a carriage return.
Find attached the rule and assets, and make sure to check that the assets path is right for your project. This rule may also be imported onto any leaf shape in your own rules, using the "import" statement in CGA. If you like it or have questions, let me know.