I see a couple of old posts regarding the use of subtypes in Arcade expressions. Has there been any movement on this? This is really basic functionality that should be supported without having to develop a consensus in my opinion.
Greetings Kieth,
I did find some documentation which suggests this may already be available?
Data Functions | ArcGIS for Developers
Seems like sub types is included here.
I hope this helps,
-Andrew W.