I'm in this situation all the time. Simple solution if you're worried about it: alphabetize them by first name. It's fair and if people actually care about crap like this, they can fuck off in general. At least if you're consistent with that, they can never complain. It's insane to me that it's a thing, but people are fragile and it matters a lot to some of them
I really hope that the people I'm sending emails to take time to read the message and respond instead of looking at the order they are copied
I only look to see if I need to respond (to:) or if it's something I need to be aware of (cc:) I don't give a fuck if I'm the last on the list or whatever
Yeah, if I'm replying to an existing thread, it's whatever order Outlook defaulted to. If I'm originating an email, alphabetical. Though I do it by last name (then first in the case of a tie).
The real life hack would be to update your resume if you work with anyone senior to you who may give a slight shit about this and publicly shaming them if they tell you to do it.