Upgrade Python 2.7 to 3.8

My team has a lot of scripts written in Python 2.7. Now we have to upgrade it to Python 3.8. I found this link https://pythonconverter.com/#creators and it worked for me. Unfortunately my company policy does not allow to use on-line tools hence I have to come up with other solution. Go into each script and modify it manually " would be very time consuming operation. Could you propose other way of conversion? Maybe some other tool or script or anything that would allow me do conversion automatically " or almost automatically?
Thanks