function mainCopyFolder() {
  
  var folderIdSrc = "フォルダID"; // コピー元のフォルダid
  var folderNameDest = "新フォルダ名"; // コピー先のフォルダ名
  
  var folderSrc = DriveApp.getFolderById(folderIdSrc); 
  var folderDest = folderSrc.getParents().next().createFolder(folderNameDest); 
  
  copyFolder(folderSrc, folderDest);
}

function copyFolder(src, dest) {
  var folders = src.getFolders();
  var files = src.getFiles();

  while(files.hasNext()) {
    var file = files.next();
    file.makeCopy(file.getName(), dest);
  }

  while(folders.hasNext()) {
    var subFolder = folders.next();
    var folderName = subFolder.getName();
    var copyFolder = dest.createFolder(folderName);
    copyFolder(subFolder, copyFolder);
  }  
}