Check out the FeatureSet functions.
Looks like this. Just a query into the other layer, then return the value (there will be just 1 found on my workflow so can use first). For you you may want to use Intersects instead of filter then it will figure out the polygon spatially.
var sql = "PointID = '" + $feature.PointID + "'";
var tbl = Filter(FeatureSetByName($map,"Points", ['Supplementals'], false), sql);
return First(tbl).Supplementals
Intersects would be something like
var WYplots = Intersects($feature,Filter(FeatureSetByName($map,"WY Plots", ["PlotID"], false), sql));
Hope that helps
https://developers.arcgis.com/arcade/function-reference/data_functions/