How do I support a younger manager without competing?

You have found something many people twice-blessed with experience never manage: you can work well for a younger boss without treating it as a demotion or a duel. That ease is a real strength. It means you have made peace with where you are and what you want, and that peace lets you actually help. The gift you bring is rare. A younger manager often carries the weight of proving themselves, half-braced for the veteran on their team to challenge them. When you show up as an ally instead, offering perspective without grabbing for the chair, you become the person who makes their job possible. That is quiet power, and it serves everyone. Keep doing what you are doing, and add one thing: tell them, plainly, that you are in their corner. A manager who knows their experienced report is not a threat can lean on you fully, and that is where you do your best work. You are not competing for the seat. You are making sure whoever sits in it succeeds.