public ActionResult ExportExcel()
{
 var empData = GetEmpdata();
 using (XLWorkbook wb = new XLWorkbook())
 {
 var sheet1 = wb.AddWorksheet(empData, "Employee Records");
 sheet1.Column(1).Style.Font.FontColor = XLColor.Red;
 sheet1.Columns(2,4).Style.Font.FontColor = XLColor.Blue;
 sheet1.Row(1).CellsUsed().Style.Fill.BackgroundColor = XLColor.Black;
 sheet1.Row(1).Style.Font.FontColor = XLColor.White;
 sheet1.Row(1).Style.Font.Bold = true;
 sheet1.Row(1).Style.Font.Shadow = true;
 sheet1.Row(1).Style.Font.Underline = XLFontUnderlineValues.Single;
 sheet1.Row(1).Style.Font.VerticalAlignment = XLFontVerticalTextAlignmentValues.Superscript;
 sheet1.Row(1).Style.Font.Italic = true;
 sheet1.Rows(2, 3).Style.Font.FontColor = XLColor.AshGrey;
 using (MemoryStream ms = new MemoryStream())
 {
 wb.SaveAs(ms);
 var file = File(ms.ToArray(), "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet", "Sample.xlsx");
 return file;
 }
 }
}
private DataTable GetEmpdata()
{
 DataTable dt = new DataTable()
 {
 TableName = "EmpData"
 };
 dt.Columns.Add("Code", typeof(int));
 dt.Columns.Add("Name", typeof(string));
 dt.Columns.Add("Email", typeof(string));
 dt.Columns.Add("Phone", typeof(string));
 dt.Columns.Add("Designation", typeof(string));
 var _list = new List<Employee>
 {
 new Employee
 {
 Code = 1,
 Designation = "Manager",
 Email = "abc@hotmail.com",
 Name = "John",
 Phone = "12345"
 }
 };
 if(_list.Count > 0 )
 {
 _list.ForEach(item =>
 {
 dt.Rows.Add(item.Code,item.Name,item.Email,item.Phone,item.Designation);
 });
 }
 return dt;
}

public class Employee
{
 public int Code { get; set; }
 public string? Name { get; set; }
 public string? Email { get; set; }
 public string? Phone { get; set; }
 public string? Designation { get; set; }
}

<PackageReference Include="Amazon.Lambda.AspNetCoreServer.Hosting" Version="1.6.1" />
<PackageReference Include="ClosedXML" Version="0.102.2" />