Frankly, all the known overdeities created their entire universe (or at least their own world), so it's not exactly a job you can apply for.
Sometimes you have to realize there are some things you'll just never be able to do, like be the sole deity over all of all creation and all other deities.
Even if it would ever happen in a game, you'd have a DM who would allow it, and since the power of an overdeity is supreme and can do absolutely anything within their world/universe, it's not really suitable for a player character, even at a divine-level game, so no DM I could think of would ever allow it. After all, when you're so powerful you can will all your enemies everywhere out of existence with a thought, create hundreds of thousands of tons of treasure with a blink of the eye, create entire planets with a thought, or slay (or create) entire pantheons of gods with a wave of the hand, there isn't much point in actually playing that character.