You did not mention the name of a specific chart study or provide any source code for one of your own. So I will pick the one named "PivotPoints" that is included with Thinkorswim. The source code for this chart study is not available. So each plot must be referenced individually. I will demonstrate how to do this for the PP level pivot and you can work out how to apply this to the rest.
input showOnlyToday = No;
input timeFrame = {default "DAY", "WEEK", "MONTH"};
plot levelPP = PivotPoints(showOnlyToday, timeFrame).PP;
def lastBar = IsNaN(close[-1]) and !IsNaN(close);
AddChartBubble(lastBar, levelPP, "PP", Color.MAGENTA);
This places a magenta colored chart bubble displaying "PP" on the last bar on the chart at the PP pivot level.