Welcome.
The release-upgrade process will not lose you setup, configs, or manually installed packages; we perform Quality Assurance testing of that process & report all findings we have (checklist can be seen here, and if we consider any findings are of benefit to end-users, we include them in the release notes.
Thus when you decide the time is right to release-upgrade to Lubuntu 23.10 (mantic) you should backup your data, then perform upgrade after reading the release notes & our upgrade instructions (I’d also recommend reading the Ubuntu 23.10 release notes too, as they can contain specific hardware details that apply to main Ubuntu & all flavors such as us).
eg. If you read https://lubuntu.me/jammy-released/ you’ll note we had specific instructions in the section titled “Notice about upgrading from Lubuntu 20.04 LTS with LXQt:”, thus it’s always good policy to read the release notes before upgrading. This applies to all Ubuntu products, in fact to most non-Ubuntu products as well.
As for backups, chances are you won’t need them, however you should always assume you will - so create good backups.
Also FYI: You can also re-install a Lubuntu system non-destructively, it’s a testcase we check for somewhat regularly; eg. read Testing Checklist - understanding the testcases where it’s called “Install using existing partition”; ie. I have a jammy or 22.04 system here I don’t perform normal apt full-upgrade on, but re-install it ~weekly as a QA testcase, then reboot it & start my normal music playlist using my non-standard music player (ie. ensuring my ‘manually installed’ packages or music-player in this example were re-installed) & my datafiles (mp3s here) were not lost. With my music playing on the freshly installed system I check my system to be ~unchanged post-install, except for metadata & packages (it’ll have a newly installed Lubuntu/Ubuntu binaries etc) but my datafiles are untouched, my configs remain etc. Do note: Any system/global changes I’d made that were stored in system directories (which are erased prior to re-install) I’d expect lost during this type of re-install; but all changes made on a user-level (ie. saved in user directory) I expect to survive. I’ve giving this only as information. If I have problems on a release-upgrade & decide I don’t have time to fix them… this re-install process is one of my backup strategies.
Also note: Our Quality Assurance testing involves only Ubuntu repository software, ie. no 3rd party… Some third party is packaged to work on release-upgrades, alas some is not; thus it’s not supported by Ubuntu/Lubuntu.
FYI: My primary PC was an artful install (ie. 17.10) & I performed six-monthly release-upgrades from 2017 until into 2022 or kinetic (22.10) with few issues… (the only major issue being the LXDE to LXQt change - we said to re-install for a reason!) until eventually that system’s power supply died & I decided I need to replace that box… I expect the same on my replacement PC which was an lunar install (23.04) and has already bumped once now being on mantic (FYI: this new box is running many of my older boxes configs; though I started fresh with LXQt configs instead of the LXDE->LXQt mess my last box had)