Older siblings don’t get practice rounds. Someone smaller is always watching how you handle it.

First children get handed the job with no rehearsal. Every rule in the house gets tested on you, every mistake happens for the first time, and there is no older version of yourself to ask about any of it. Meanwhile somebody four years behind is watching how you handle being told no, losing a game, failing a test. You did not sign up to be the demonstration, and you are one anyway.

Be kinder to yourself about the mistakes, since you are doing it without a map. And use the position rather than resenting it. Let the younger one see you handle one hard thing badly and then try again.