Clothing Design Help (Help with Achieving a Certain Pattern)

Hello! My name is Neuvillaire and I just started hardline clothing design around two weeks ago so I’m relatively brand new.

I created the jacket for the outfit I’m trying to recreate but I’m a little stuck on the pants. The pants have this cosmic look to them but I don’t know how to achieve that look.

Do y’all have any tips/ideas on how to mimic a cosmic-like effect for my pair of pants?

Pants I'm trying to replicate
Jacket