Answer:
Okay, so,
Step-by-step explanation:
Maybe you could suddenly wake up one day, dramatically shorter than the day before. Or you could eat/drink something mysterious (Alice in Wonderland vibes) that causes you to shrink.
Instead of just becoming small, you could turn into a small animal instead, like a mouse. The based on that you can write what it's like to escape from mouse traps and steal food from a kitchen.
You could write from a point of view of a tall person who wishes that they weren't teased for their height. They find a mysterious person who says that they will grant their wish, only, it doesn't go too well and the person ends up smaller than they wanted to be.
I hope these ideas gave you some inspiration...