Career fairs and some colleges may have writing centers or people that assist with cover letters, resumes, etc.
If you dont have that opportunity, I would search some up. Find ones that resonate with you and copy it but make it your own. Thats what I have done and ive been fairly successful. You can tie personal stories in them and still make them sound professional.
I prefer them fresh but if needed, I retoast them when I get home especially with undercooked fries like Wendy’s . Ensures they are hot and crispy