What would be the best way to convince a professor to waive late submission penalties? I am a grad level student and I am completing my last course this semester. 
The professor is reducing our grade by 20%/day if we submit our assignment late.
It is a lot. For example, my grade is 18/20 and he reduced it by 4 because I submitted it a day late. My total GPA is A+. It is a significant amount of grade that he is taking off. This will ruin my grade.

I understand that a late submission is not good. Having said that, I have always been trying my best to submit them on time. His assignments were more difficult than what he was teaching us during lectures and I always need to study extra books and material to solve problems.

I was thinking of sending an email and asking for him to waive the penalties. Especially now due to COVID it is somehow cruel to enforce these penalties. 

What would be the best way to convince a professor to waive late submission penalties?

Reason for late submission: Due to my research internship, I have been working part-time in a company in another city (not the city that the university is located). So it was pretty hard for me to keep up with the deadline. Before COVID, I had to even commute in between cities to attend classes and that drained me. 

Edited: I wrote this letter, please feel free to edit or add more details.


  Dear zyx,
     I am writing regarding the late-submission penalties.
  
  Due to my research internship and displacement, It was pretty hard for me to keep up with the deadlines.
  
  During this time I had to commute in between cities and I had only slid to follow up the course and solve assignments that I can save them for submitting my assignments earlier.
  
  Not accessing the in-person classes made me spend hours studying other references to solve my assignments.
  
  So I was wondering if you could please waive late submission penalties?
  
  Best regards,
  
  XYZ
Professors will say no by default to all such requests, but a lot of the time they secretly want to say yes, so you need to help them help you by providing all the relevant context, being logical and reasonable, and generally convince them that you are worthy of their attention and understanding.
Here is my attempt at a draft email.

Dear Professor xyz,
my name is ZYX, I’m a student in your Programming for Programmers class. I submitted the first class project one day late on February 17 and as a result you imposed a 20% late submission penalty, which reduced my project grade from 18/20 to 14/20.
I know that this penalty is in the course policies and accept that there is a good reason for such penalties and that you have the right to decide such things. But I wonder if you considered that such a high penalty may be unreasonably harsh? I am an excellent student and have worked very hard to maintain an overall GPA of A+ in the program. Because of the penalty it seems almost certain that my final grade for the class will end up lower than what my performance would merit without the penalty, which in turn would lower my overall GPA and future academic and career chances. The consequences seem disproportionate relative to the one time mistake of submitting an assignment late by just one day.
I therefore want to ask respectfully if you might consider waiving or at least reducing the penalty for this late submission.
I do sincerely apologize for the late submission, and for not contacting you in advance of the deadline to request an extension (something that in hindsight I obviously should have done when I realized I was going to be late). Normally I am very good at keeping up with my workload, but back in February, because of a research internship I was doing at [name of company], which required me to commute back and forth between [name of city 1] and [name of city 2] and took up a lot of my time and energy, my commitments ended up piling up in an unexpected way, which caused me to fall a little behind and miss the deadline. I nonetheless worked diligently to catch up and ended up managing to submit what I think you’ll agree is a high quality project the next day.
Thanks for your consideration. I hope you understand my anxiety and do not think less of me for making this request. In this difficult period when students like me are facing an uncertain job market and other unusual difficulties related to the COVID-19 crisis, we could use a bit of leniency.
Regards,
ZYX