I also was not sure if XenForo even had a sub-account feature like Jcink has. That would be a neat one on a forum where you may just use a general staff account to post announcements, etc.
Spicy hot take: subaccounts are the wrong tool for that sort of job because they're still tied to the master account.
I've long thought there needs to be a better way that subaccounts in general, and I actually started work on a better way.
So, first up, personas. (In RP, these are the characters) You post as a persona rather than as an account, activity/avatars/etc. in posts hangs off the persona rather than the account. This also means that moderation/PMs/notifications/alerts can be tied back to an account rather than a persona per se, which is just more convenient for everyone (though this *is* solveable in the subaccounts world with extra work)
Then you add in the concept of a shareable persona. Maybe it's shareable with all admins, maybe it's shareable with other groups. This in your case is the 'staff account'. That way it's not tied (overtly) to any actual admin if you genuinely want to make a 'staff account' that doesn't have the same personality issues (e.g. favourite admins)
In an RP context this also means that if you're in a fandom with some specific canon characters that are core to the fandom that you need to keep around for site plots (my goto example for this is Dumbledore in most Harry Potter sites; you need him for the occasional RP interaction but you don't necessarily need him to be regularly playable and you might want to share this with other admins)
I'd gotten to the point where I'd separated accounts and personas, and it was possible to move personas between accounts if needed (e.g. if I needed to post something as Dumbledore I as an admin could move it to my account, but it was a bit clunky, would be better as a shareable NPC)
The reality: subaccounts in the classical implementation is mostly that way out of convenience rather than necessity; easier to get going with 'now each subaccount has an avatar because it's really an actual account' but when you get into notifications, PMs, moderation, it becomes a nightmare, and the deeper you go the worse it gets.