lakshya they need to have no limit on title
As far as I know, this is impossible due to database limits and setup that FreeFlarum uses. An extension could extend the limit, but it can never be limitless due to how databases work.
All you can do right now is politely ask them to structure the titles to the point and without unnecessary words in order to make your forum more structured and organized. Also, you could have a "Help Wanted" tag, depends on your use case.
You see, a forum can never be perfect and you'll always need someone to control the content. So, I'd recommend to make some discussion guidelines and control inappropriate one manually. FoF Filter and other extensions (Approval, etc.) can help you to some extent.