'visualize what' is a correct and usable phrase in written English.
It can be used when you want someone to imagine a scene or situation. For example, "Visualize what it would be like if you could fly".
It is almost impossible to visualize what is happening there".
He even stood on the mound to visualize what yesterday might be like.
I could not even begin to visualize what he was talking about.
She can visualize what others can't, and think of deals that others don't.
"You have to help people visualize what the risk means," Mr. Jacobs said.
Now, you get to visualize what retirement life will be like.
It's a wonderful term because everyone can visualize what happens next.
Visualize what the photographer is seeing through the lens and trust your intuition.
When he tries to visualize what the future will look like, everything he sees "looked like an advertisement".
The musical closes with a kiss on the lips, and it's hard to visualize what happens next.
This is a moment for Spicer to collect himself and visualize what a good day would look like.
