The best option is to upgrade to Ubuntu 20.04.2.0 LTS (Focal Fossa), which is supported until April 2025 with security and maintenance updates, guaranteed.
You have 2 options:
- A clean install by downloading the new release ISO file and making a bootable USB Flash Drive or DVD (make sure you do a full backup of all your files before installation of the new system)
- Upgrade your existing installation by issuing the following command:
sudo do-release-upgrade -d
More information here: https://www.linuxtechi.com/upgrade-ubuntu-18-04-lts-to-ubuntu-20-04-lts/
Let me know if you have any questions.