You can't chose to only show the highest value, but an alternative could be to show the highest and lowest values by giving them a certain color?
Expression Front End:
IF(Sum(Value) = Max(Total Aggr(Sum(Value),City)),Green(), // Highest Value
IF(Sum(Value) = Min(Total Aggr(Sum(Value),City)),Red() // Lowest Value
,LightGray())) // In between bars
What that looks like:
It might be possible with an extension, but I haven't looked around for that.
Edit: If you are using this to present further later and want to only show it then you can do it in the Stories and there use the highlight highest value. But if it is for front-end and dynamic Qlik Sense app use then no.