Increasing the size of numbers in a legend bar

Question

I would like to know how you go about increasing the size of numbers which appear in a legend to make them larger than the default (which is too small for publication purposes).

Example:

ContourPlot[Fn[1, 0.1, n, v], {v, 0.1, 5}, {n, 0.1, 1}, 
  ClippingStyle -> Automatic,
  PlotPoints -> 100, 
  ColorFunction -> "BlueGreenYellow", 
  LabelStyle -> Directive[Thick, Large], 
  FrameLabel -> {Style["V", Large], Style["n", Large]}, 
  PlotLabel -> Style["(a)", Large],
  PlotLegends -> Automatic]

Answer 1

ContourPlot[v^2 - n^2, {v, 0.1, 5}, {n, 0.1, 1}, 
 ClippingStyle -> Automatic, PlotPoints -> 100, 
 ColorFunction -> "BlueGreenYellow", 
 LabelStyle -> Directive[Thick, Large], 
 FrameLabel -> {Style["V", Large], Style["n", Large]}, 
 PlotLabel -> Style["(a)", Large], 
 PlotLegends -> BarLegend[Automatic, LabelStyle -> {FontSize -> 30}]]