I assume the x-data are categorical, because otherwise this is straightforward.
Perhaps this —
x = 1:5;
y = rand(1,5);
xlbl = categorical(["A","B","C","D","E"]);
figure
bar(xlbl,y)
title('Original')
Ax = gca;
% get(Ax)
xv = Ax.Children.XData;
yv = Ax.Children.YData;
[~,idx] = sort(yv, 'descend');
xv = reordercats(xv, idx);
figure
bar(xv(idx), yv(idx))
title('Sorted')
.
