The 10.2.7 runtime has the class 'AttributeLabelClass' that allows you to format the labels for graphics and add it to a GraphicsLayer such that all Graphics with a certain attribute will render the same way.
Does anyone know if anything like this survived into the 100.0+ time-frame? I've been looking all over for this with no luck (which usually means it's right in front of my nose).
I'm fairly sure something like this exists because I've seen prototype demos of the efforts to resolve label confliction rendering issues.
We're hoping to have this feature back in Update 1. The public API might not be fully complete by then, but you'll at least be able to set everything with the json definition, and a more full-blown API for all the properties by Update 2.