I used the recorder to get this code, and it seems to work?

function main(workbook: ExcelScript.Workbook) {
    let selectedSheet = workbook.getActiveWorksheet();
    
    // Set range A1:B3 on selectedSheet
    selectedSheet.getRange("A1:B3").setValues([["A",1],["B",2],["C",3]]);

    // Insert chart on sheet selectedSheet
    let chart_1 = selectedSheet.addChart(ExcelScript.ChartType.columnClustered, selectedSheet.getRange("A1:B3"));

    // Change fill color for point on series on chart chart_1
    chart_1.getSeries()[0].getPoints()[0].getFormat().getFill().setSolidColor("ffc000");
}