tl;dr You can lead a horse to water, but you cannot make it drink.
When I was moderating I tried various approaches. I found that most stickies and wiki's (the excellent supercharging wiki maintained by
@CMc1 and
@cezdoc being pretty much an exception) didn't get read so I stopped bothering to maintain them. The 2021 new owners thread suffered from poor timing as it coincided with the Freemont to China transition. Wiki's have a problem on this forum as there is no way to limit who has access which can result in conflicts in updates and it ultimately comes down to a moderator to sort out the mess. Likewise stickies are not perfect either as too many (especially when not within the organic posts) are glossed over and you end up with some important info in stickies that might be better served in the organic posts if you could ensure that they could self maintain themselves on the first organic page or so of threads to remain useful/visible - not so easy with the cyclic nature of Tesla ordering/releases/features etc as things become highly active, then less so, then active again.
The best approach that I found was actively moving threads to a selection of threads on similar topic but it took a lot of time and effort, and wasn't always possible, especially with fast moving threads or when people post multiple questions and/or OT comments/questions in the same post. Plus some users took great exception at having their posts moderated and can get quite personal with attacks on moderators - something that many do not get to see.
Another thing that seems to work well initially are community posted links back to existing similar threads, but it doesn't take long before that link is swamped by more answers by which time you then have multiple active threads on the similar topic. But at least the poster got their question answered and hopefully will know that another thread with probably a more thorough discussion exists although not always as current as things do change over time so its a trade off between stale information and another thread - as most people only seem to read the tail end of long threads and they are clearly dated its normally pretty easy to track when data in a thread has become stale especially as its easy to search a single thread and filter by post age.
As well as OT/multiple question threads, another issue are threads with vague or clickbait titles that give no indication as to the real contents for those scanning or searching. I always tried to gives titles some sense, but again, a lot of time and effort. Likewise tagging threads too to make them more search friendly.
Threadloom search in particular (iirc its not the default and other search engines are available too) is very powerful especially if you roughly know what you are looking for. Its easy to narrow a search scope to a particular sub forum or even a single thread. But even still, its not going to be 100% and requires a little effort which at the end of the day, all the while there is an active community willing to answer, its easier to simply repeat the same questions and comments no matter how easy it is to find the answer elsewhere or in another thread or even in the same post.
I even started to curate a list of typical questions with links to the active threads on the subject, but the list got so long it ceased to be useful and remains a hidden thread on here somewhere.
Unfortunately, this takes a lot of effort from a small group of people. When I was planning to stop moderating I made sure that I would be replaced by at least two others that were UK subforum regulars - very few takers at the time to the shout, but if anyone is still interested, I am sure the current mods would welcome more hands if you asked them.