I need an adjective that conveys the meaning of things going the way you want them to.
For example if you are a king you would want everything during your reign to go your way.
When I am king, I want a ______ reign.
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When something isn't going the way you want, it opposes you. When nothing opposes you, you are unopposed. So you might say
When I am king, I want an unopposed reign.
Alternatively, your could use unobstructed, uncontested, or unchallenged.
This covers those thing one would explicitly want, as you say in your opening sentence.
However, if you want to go beyond what you openly want, then better than being unopposed would be that everything fortuitously falls in place. (It would be like winning the lottery when you didn't even by a ticket! Who wouldn't want that? But it's not really what most people seriously want in the sense that they might expect it to happen.) For that, you might say you want a charmed reign, where charmed means "marked by good fortune or privilege" (Dictionary.com #1). But charmed is not a commonly used word today, so you might simply say
I want a reign favored by fortune.
I want a prosperous reign.
This is where auspicious comes in. It is good fortune not just for what is wanted, but for everything else, as well. But I don't think, based on your first sentence, this is what you asked for.
or thriving which has multiple meanings which seem relevant
Not causing any problems or difficulties.
When I am king, I want a trouble-free reign.