Models:

    public class UserInfo
    {
        public string UserName { get; set; }

        public int Age { get; set; }
    }
    public class DemoResponse<T>
    {
        public int Code { get; set; }

        public string Msg { get; set; }

        public T Data { get; set; }

        public static DemoResponse<T> GetResult(int code, string msg, T data = default(T))
        {
            return new DemoResponse<T>
            {
                Code = code,
                Msg = msg,
                Data = data
            };
        }
    }

Download view page:

DownLoad.cshtml:

        @page "/download"
        @model BlazorServerApp.Pages.DownloadModel
        @{
        }

Download.cshtml.cs:
        using BlazorServerApp.Data;
        using Microsoft.AspNetCore.Mvc;
        using Microsoft.AspNetCore.Mvc.RazorPages;
        using OfficeOpenXml;

        namespace BlazorServerApp.Pages
        {
            public class DownloadModel : PageModel
            {
                public IActionResult OnGet()
                {
                    //queryt the data dabtase and get the data.
                    var list = new List<UserInfo>()
                    {
                        new UserInfo { UserName = "catcher", Age = 18 },
                        new UserInfo { UserName = "james", Age = 20 },
                    };
                    // If you use EPPlus in a noncommercial context
                    // according to the Polyform Noncommercial license:
                    ExcelPackage.LicenseContext = LicenseContext.NonCommercial;
                    var stream = new MemoryStream();

                    using (var package = new ExcelPackage(stream))
                    {
                        var workSheet = package.Workbook.Worksheets.Add("Sheet1");
                        workSheet.Cells.LoadFromCollection(list, true);
                        package.Save();
                    }
                    stream.Position = 0;
                    string excelName = $"UserList-{DateTime.Now.ToString("yyyyMMddHHmmssfff")}.xlsx";

                    //return File(stream, "application/octet-stream", excelName);  
                    return File(stream, "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet", excelName);
                }
            }
        }