多くの標準的な矢印形状が利用できます

ScottPlot.Plot myPlot = new();

ArrowShape[] arrowShapes = Enum.GetValues<ArrowShape>().ToArray();

for (int i = 0; i < arrowShapes.Length; i++)
{
    Coordinates arrowTip = new(0, -i);
    Coordinates arrowBase = arrowTip.WithDelta(1, 0);

    var arrow = myPlot.Add.Arrow(arrowBase, arrowTip);
    arrow.ArrowShape = arrowShapes[i].GetShape();

    var txt = myPlot.Add.Text(arrowShapes[i].ToString(), arrowBase.WithDelta(.1, 0));
    txt.LabelFontColor = arrow.ArrowLineColor;
    txt.LabelAlignment = Alignment.MiddleLeft;
    txt.LabelFontSize = 18;
}

myPlot.Axes.SetLimits(-1, 3, -arrowShapes.Length, 1);
myPlot.HideGrid();

myPlot.SavePng("demo.png", 400, 300);