Question: To provide more details, should you flush out or flesh out your plan?

Answer: flesh out How to remember it: Think of fleshing out a skeleton.

To flesh out something is to give it substance, or to make it fuller or more nearly complete.

To flush out something is to cause it to leave a hiding place, e.g., "The birds were flushed out of the tree." It can also be used figuratively, as in "flush out the truth."