Will the Edit (beta) widget support multiline input in future? This option would pair nicely with the multiline view in the Feature Info widget. The current single line view makes it difficult for users to edit text in the widget.
The edit widget will honor the multiline setting if you have set up a form on the map.
However, it appears as if you can only see two lines at a time in the form, but are able to scroll in the field.
You are able to resize the width of the field in the live edit widget, but not the height.
ESRI really needs to fix this in future updates of Enterprise Portal/ArcGIS Online. You can manually change the CSS theme files in the Enterprise Portal installation to allow the multiline text field to be expanded vertically. For some reason, the CSS is written to restrict resizing to horizontal only, which seems like a mistake.