It would be easier and faster to enter some information about you then the program generate your cover letter, whatever company and field you applying for, I create this application using Tkinter for GUI and Reportlab to generate PDF file ready to send for the company you applying for.
Tkinter to build GUI you need to install the following: pip install tk-tools pip install tk
Reportlab to generate PDF file pip install reportlab
Reportlab user Guide : https://www.reportlab.com/docs/reportlab-userguide.pdf . Tkinter documentation : https://docs.python.org/3/library/tk.html
Watch how it works here: https://youtu.be/RKWO7KxhkEk