To dynamize your prompts with the permutation in Midjourney you just have to put between braces your (images, settings, subjects, environment...etc.).
For example :
a {red, blue, green} box
will generate 3 prompts:
a red box
a blue box
a green box
This is only available for the PRO subscription
------
This video is part of the playlist dedicated to Midjourney:
• Formation Midjourney
------