https://www.pbainbridge.co.uk/2018/12/copy-doc-and-add-paragraphs.html

Copy Doc and add Paragraphs.gs

function copyDoc_Paragraphs() {

  // document ID of the file to be copied
  var docId = 'insert your file ID';
  
  // instruct DriveApp to get this document
  var templateDoc = DriveApp.getFileById(docId);
  
  // folder ID of where the copied file is to be saved
  var folderId = 'insert your folder ID';
  
  // instruct DriveApp to get this folder
  var destinationFolder = DriveApp.getFolderById(folderId);
  
  // copy the file to the destination and get the Url
  var newDocUrl = templateDoc.makeCopy('new doc', destinationFolder).getUrl();
  
  // open the file by the Url
  var newDoc = DocumentApp.openByUrl(newDocUrl);
  
  // get the body of the document
  var docBody = newDoc.getBody();
  
  // replace the tag with 'Eric'
  docBody.replaceText('<<Name>>', 'Eric');
  
  // add 5 paragraph lines
  for (var i=1; i<6; i++) {
   docBody.appendParagraph('this is paragraph ' + i); 
  }
  
}