Hey. I wish to join someone in ROBLOX but they are not friended, and they do not have their joins on and are nowhere near me IRL.
Are there any extensions I can use to join them externally outside of ROBLOX which will make me able to join their server they are in? I’d like some solutions to be able to join them without friending them and without their joins on.
Thanks. 
No, there’s no extensions that allow to join any player. And I’m pretty sure even if it did exist, it would be breaking the ToS.
Pretty sure, propular YouTubers or/and developers wouldn’t want to be followed everywhere.
This is someone who I know IRL, though. Okay then! Any other solution? Else I’ll tick the next message as solution.
You can have them enable their privacy settings to be able to join to either Everyone or Friends and users I follow (they would have to follow you in Roblox, then you can join them)