This can be achieved today with a little data manipulation.
You can create a new field in your feature layer that combines information from several fields into a single field. Then, that new field can be set as the description field in the map tour so all the information you want is shown.
This workflow is very powerful and allows you to format the description field with multiple paragraphs, lists, links, and more.
You can create this new field using the field calculator on the ArcGIS feature layer item page or manipulate the data in your favorite spreadsheet app, like Excel or Google Sheets, and upload the CSV as a new feature layer.