replaceTextExt

function replaceTextExt(fileTag, refGID)
{
          var fileId = refGID; //Gets GID for blob being used. 
          var tag = fileTag; //Tag where item will be appended 
          var style = {};
          style[DocumentApp.Attribute.HORIZONTAL_ALIGNMENT] = DocumentApp.HorizontalAlignment.CENTER;
          
          var blob = DriveApp.getFileById(fileId).getBlob(); //Gets image blob  
          
          if (newBody.findText(tag) != null) //Makes sure tag exists
          {
            var replacedParent = newBody.findText(tag).getElement().getParent().asParagraph(); //Identifies tag location
            var clearTag = newBody.replaceText(tag, ""); //Removes placeholder tag
            
            replacedParent.appendInlineImage(blob).setAttributes(style); //Adds image at tag location using set "style"            
          }
}