As far as I can tell, the expressions and calculations available in EB are pretty basic, and more for numeric fields.
Arcade is not available in Experience Builder (yet). Also, you're not able to use a variable (static or calculated) to populate a style element like the background color of a list item. At least, not directly in the EB editor. I can imagine it may be possible, but probably requires custom JS coding.
- Josh Carlson
Kendall County GIS