https://support.office.com/en-us/article/command-line-switches-for-microsoft-office-products-079164cd-4ef5-4178-b235-441737deb3a6#ID0EAABAAA=Excel

//************
Excel.Application xlApp = new Excel.Application();

xlApp.addCommandLineParameter("/u:XXX");

xlApp.addCommandLineParameter("/p:YYY");

//************ xlworkbook = xlapp.Workbooks.Open(fileExcel, 0, true, 5, "", "", true,Microsoft.Office.Interop.Excel.XlPlatform.xlWindows,"\t", false, false, 0, true, 1, 0);

//*********
https://docs.microsoft.com/en-us/dotnet/api/microsoft.office.interop.excel.workbooks.open?view=excel-pia