You can but its a theme park ride and not the real Aslan.

I wish I could travel between worlds like in The Magician's Nephew.

Right, you can now travel between worlds just like in The Magician's Nephew, via the Wood Between the Worlds... only (unlike Digory and Polly) you forgot to mark which pool you first came out from, which means you may just have to make a LOT of visits to other worlds before you find the way back to your own.

I wish I could control the weather.

Presto, you now control the weather! However, everyone now knows about this power of yours and makes increasingly complicated demands of you every day.

I wish I didn't have writer's block.

You no longer have writer's block! But you find you can only muster the motivation to write for a 20-second time frame per week, so it takes you months to even write a single page!

I wish I had an unlimited supply of Diet Coke.

Congratulations, you now have unlimited Diet Coke... from 1983. Enjoy. If you can.

I wish I had a full-size catapult!

As you wish! However, it's a very old catapult, and it doesn't function and is barely staying together.

I wish meals didn't take significantly longer to prepare than to eat.

Ta Da! You have your wish. A plethora of various food suppliers from Pizza Hut, to Meals on Wheels, will supply your every need. But, unfortunately, having been obliged to "self-isolate", due to local worries about communicable diseases, you will, over time, find the range of such self suppliers becoming, over time, increasingly boring & unappetizing.

I wish that for the rest of the year, we have plenty of rain.

Voila! Rain, rain, rain! But oh no - it's raining frogs. Not only does this not help the land, but now you have an epic frog infestation like the world has never seen! You start going crazy from the eternal "ribbit" sound that never goes a way....

I wish my feet stopped getting so cold at night!

Your feet no longer get so cold at night. But the rest of you gets excessively hot during the day.

I wish I could learn to play the saxophone in three months.

Congratulations! You've learned how to play the saxophone within three months, much faster than normal. Unfortunately, every time you try to play, the sound is always horribly dissonant.

I wish that I owned a magic book that allowed me to visit my favorite literary worlds (like Narnia )

Presto! You now are the owner of a magic book that allows you to visit your favorite literary worlds! Unfortunately, you can only visit for 30 seconds.

I wish that someone would do my homework for my graduate class.

~Wunder

Someone does do your homework for your graduate class... and gets all the answers wrong.

I wish the entire world would be instantly free of the COVID-19 pandemic.