Using chart templates - donkma93/EPPlus GitHub Wiki

EPPlus 5 also support chart templates (with the crtx extension) via the AddChartFromTemplate method. Crtx files can be exported from Excel from any chart. Chart templates will work for chart types implemented in EPPlus.

//Add an Area chart from a template file.
var areaChart = (ExcelAreaChart)ws.Drawings.AddChartFromTemplate(FileInputUtil.GetFileInfo("15-ChartsAndThemes", "AreaChartStyle3.crtx"), "areaChart");

var areaSerie = areaChart.Series.Add(ws.Cells[2, 7, 26, 7], ws.Cells[2, 6, 26, 6]);
areaSerie.Header = "Order Value";
areaChart.SetPosition(51, 0, 10, 0);
areaChart.SetSize(1000, 300);
areaChart.Title.Text = "Area Chart";

See Charts & Themes sample .NET Framework or Charts & Themes sample .NET Core