Hi Onel,
Both of these maps were made in ArcGIS Online using Smart Mapping functionality.
For the home heating type map, we use a "predominance" style for the polygon data, turn the transparency up. Then copy the layer, and use "predominance and size" style with the same attributes & colors right on top of it. Here's some tips on predominance mapping: https://www.esri.com/arcgis-blog/products/arcgis-online/mapping/whats-new-in-predominance-mapping-ap...
For the unemployment map, we used "above and below" symbology with proportional symbols. Above and below allows you to center your color ramp on a critical value. This blog post has some good info about it in the "Above and Below Theme" section: https://www.esri.com/arcgis-blog/products/arcgis-online/mapping/better-breaks-define-your-maps-purpo...
Best of luck with your bamboo map!
-Diana
