I have Enterprise 11.3. I'm in a webmap trying to learn Arcade expressions. I have a layer highlighted in Contents panel, show Properties, click on Popup > Attribute Expressions > Add expression. In Arcade expression window, I click on Profile variables and there is no $map variable, only $feature, $userInput, and $graph. I tried ArcGIS Online too but I don't see it in there either.
https://developers.arcgis.com/arcade/profiles/popup/