Just say ‘I’m curious when you decided to be the manager?’ in a light-hearted way and lead the convo by saying, ‘If I do X, then will you do Y?’
So you split the task they’re bossing you to do, so you end up working as a team and they then say yes to your request. You’re demonstrating you’re equal then. If they say no, then don’t do it, just say, ‘Okay, I’m gonna do Z instead’.
The last time I did that, it worked a treat.