Major OS updates are automatic, there's nothing you need to do. If you are on the Stable channel, you need to wait for the Android 14 update to pass through Alpha and Beta channels first before it comes to your device.
By default, the updater checks for updates every 4 hours and displays a collapsed (minimized) notification if the system is already up-to-date. Make sure notifications for the system updater are enabled in settings > system > system update > notification settings. If you wish, you can also toggle off the "Minimize" option for the "Already Updated" notification channel so that you don't have to pull down the notification shade in order to see the notifications.