shameekbiswas you can achieve parts of this using Tags and the Flarum permission system. You could make a wiki tag under which you allow any user to edit posts.
It might be a bit complicated depending on the exact configuration you want since in Flarum the base permission must be more liberal than individual tag permissions, so you would have to apply permissions on all other tags that aren't the wiki tag.
This would also allow editing any reply unfortunately. But by using a variation of this extension for example a new permission could be introduced that just controls who can edit the first post https://discuss.flarum.org/d/26521-advanced-post-permissions
Where the extension would be most useful is probably to manage and show the list of users who edited a post and give tools to moderators to find out who vandalized it.
