Improve the script in Google Apps Script

It is necessary to add the following functionality to the script of the table (the script itself is attached) executed in Google Sheets:
1. Name the file to be sent
2. Send the file to E-mail. Mail
3. Add text to the letter
4. Add a signature to the letter.
Table reference
https://docs.google.com/spreadsheets/d/1jFVV99olaVCFwdtN78CS9CXWA0nQjZ10BhlPl_HAjyU/edit#gid=1857471596

It is implemented through the sendSpreadsheetToPdf function, which must be added to the body of the script. The arguments are values from specific cells in the table.You must also keep the bulk upload script functional.