At pro 2.4 ESRI implemented attributes rules at the file Geodatabase Level which is great.
It means that when you copy or move the file geodatabase, you copy or move the rules.
It would be great to have attributes rules fully implemented in ArcGIS Online.
This would allow users to have their own QC and field calculation in hosted feature layers and web apps !
(edited 2020-07-24 to improve this description)