Turn everyone into their own fantasy

Sophie: "Ah, why would I need to bother my cute little head with trivial details? I'll just let everyone have their most desired, depraved bodies!"

A simply put statement, but a bit more difficult to implement. You don't want to go around peeking into everyone's fantasies and then transform them one by one - that would take ages! Thankfully you have a Master's degree in computer science, so you've got a knack for automation.

You create a computer to channel your powers into. For this computer you create a program that, upon being run, automatically reads the subconscious minds of everyone on Earth, creates a model of the desired form, and then transforms them into said appearance, complete with all the secondary attributes that come with it, such as superpowers, or even Divinity.

A few restrictions are required, though. You decide to disclude minors from this program, 'cause that would just be weird. Also, if any weirdo does happen to have the desired body of an omnipotent Goddess, you obviously won't grant them total omnipotence - only omnipotence in relation to everyone except you.

The computer doesn't need electricity - instead it functions on Catgirl Magic, which you happen to have in abundance.

Sophie: "Let's see... just a little, eensie-weensie jolt of magic ought to-"

You flick your ears, and the computer explodes with an overcharge.

Sophie: "Mother flubbard!"

You reform the computer, this time making it indestructible, and capable of intaking an arbirary amount of Catgirl Magic. This time the computer actually powers, and you manage to run the program.

One thing becomes immediately apparent: it's doing something. The whole city rumbles, as all the giant and giantess enthusiasts have spontaneous growth spurts. Something else spurts too, namely the train-sized hyper cocks of people who fantasize about being able to drown out oceans with their cum. Other body parts are widely hyper-ized too: thighs, butts, muscles, even lips. You're not really a fan of hyper obesity though, so you decide to remove the concept from existece so nobody would fantasize about it.

The second wave of destruction comes when people begin to take notice of their superpowers. Buildings collapse, cars are crushed and incinerated, rivers and lakes frozen, mountains thrown into the Sun... and the folks who wanted to be Gods and Goddesses make a whole different kind of a mess, breaking and twisting the laws of reality.

Notably, you yourself have remained the exact same. Apparently your original transformation was into your own subconsciously ideal body - who knew!

You deliberate for a moment on the results of your actions. The world is simultaneously being both drowned out by cum, crushed by mountain-sized boobs and the whole planet Earth is being fought over by hundreds of thousands of variously-sized giants and giantesses who wish to eat or otherwise destroy it. All in all, this seems like a bad move.

Sophie: "Hm. Nobody can really enjoy their new bodies like this. I need to make even further changes."