Thanks for sharing Michael Volz
Part of this idea could be considered implemented with the Attribute Rules that Enterprise offers. On the long term the UNME might be ported to ArcGIS Online, which would algo require the attribute rules to become available in ArcGIS Online.
My comment was more related to the new Arcade expressions (FeatureSetBy*) which were introduced in the update last december in AGOL. These functions are not available in the symbology profile of the Arcade expressions, most likely due to the performance hit this would cause. Since you can use them in the Field Calculations it would be great to have some kind of scheduled task configuration with the field calculation in AGOL to trigger the update for instance each night to make it not so static if you want to visualize something dynamically without the performance hit.
