Through a Web Map in ArcGIS Online, I'm creating a field in Feature #1 and Feature #1 is related to Feature #2. Is there a way to get the specific values in Feature #2 that are related via for an Arcade expression in Feature #1?
It's a 1 to many relate and related through a Text ID Field that they both have. 
EDIT: I think it has something to do with FeatureSetBy functions