You need to be a part of the Android beta program to get the OTA update and once you have joined the beta program the update will be installed automatically. Android 14 is not bringing big changes but it will bring refinements of performance, privacy, and security. There can be some system UI changes, including a new back button (which matches the Material You theme), a new share sheet, and more. There can be also an option to enable the transparent navigation bar by default.
A lot more features are there to explore in the upcoming Google I/O 2023 event, which will be held on May 10. Google has planned to release another beta update in May, and subsequent platform stability updates, with the stable release expected after July. So a lot more updates are coming for which you need to stay tuned.