Hi Rahul,
You did not specify where inside the plot, you can adjust that
PlotLegends ->
Placed[LineLegend[{Style["\[Xi] = 10", Bold, 14],
Style["\[Xi] = 50", Bold, 14], Style["\[Xi] = 100", Bold, 14]},
LegendFunction -> Frame, LegendLayout -> "Row"], {Center, Top}]