The explanation would be too long for a grepper answer.
So here is a link to a stackoverflow question:
https://stackoverflow.com/questions/45137395/how-do-i-upgrade-the-python-installation-in-windows-10
6
0
N
pip install [package] --upgrade
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You cannot just pip install python3 because it is not a library.
If you want to install the latest python3:
https://www.python.org/ftp/python/3.8.2/python-3.8.2.exe