So first to check are you running official or community check your full_build_string.
Check this from the install page, Install /e/OS on a Samsung Galaxy S9 - “starlte”
Downloads for starlte
- /e/OS build : A13 community
- /e/OS build : A12 official
To understand the difference between /e/OS builds check this guide
You are asking from a position of official (??) – in the title.
No OTA Upgrade for official is published and there is no published official-t build so that is not an option.
Changing from official to community is advised to Factory reset.
So change from official-s to community-t might count as a “very dirty upgrade”.
The prior question would be “Are you planning to build official-t (or maybe official-a14) ?”
Android version OTA Upgrade is the next step after a build is available.
If I was to jump ship from official-s to community-t I would Factory reset for a clean experience. Last time I said this it was pointed out in the nicest possible way that I am “conservative”.