To highlight subset of bars in a bar chart, like the one below, requires the use of custom expressions and color assignments.
In this example, we have a date anchor that we want to highlight in red compared to the other bars. This builds upon an earlier post describing creating anchor and +/- N days - you can read more here:
The dashboard contains a date parameter that we are using in the color shelf expression. Using a conditional statement, we are forcing the color output to be one of two possible string values: “highlight” or “-”
if ([Order Date] = '<<dateparam>>', 'highlight', '-')
We then want to fix the assignment of these values to color within the Colors setting. Make sure to click on “Fix color for specified values”. That will provide a list of color - value mappings you can modify.