Hey @zain 12 Eden from the support engineer team here.
At the moment, it's not possible to have the Messenger automatically open when landing on your Help Center, or through specific URL parameters. However, you may be able to use a workaround of having a chat message configured to pop up when users, leads, and visitors land on your Help Center URL, so as to call attention to the Messenger. This is an interesting feature request for the team! Let me know if there was more context you wanted to share on why you’d like to see this functionality.