How do I update my LineageOS installation?
If you go to your phone’s settings, then “About phone”, you’ll see the phone’s status with an entry at the very top called “LineageOS updates”. In there you can configure how often your phone should check for updates, and you’ll also see a list of available updates. You can tap the “Download” button to download an update, and once it’s finished downloading, the button will say “Install” and tapping that will reboot your phone to TWRP and install the update.