I updated my system using:

sudo apt-get update && sudo apt-get upgrade

And then ran the following to install python3.9:

sudo apt-get install python3.9

Which yields output:

Reading package lists... Done

Building dependency tree

Reading state information... Done

python3.9 is already the newest version (3.9.5-3~20.04.1).

0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

However, when I run python3 -V it still tells me I am on 3.8.5. How can I fix this?