How to modify gem based theme

I found a good theme that I want to use as a base, but heavily modify it, I looked for the themes files, and couldn’t find it, according to someone here

a theme can be a gem that you specify […] the actual theme files like layouts […] are hidden from you. You can expose them with a certain command to see where they are in your file system.

however, they never said what the command was, could someone help me?

Run `bundle info --path` followed by the name of the theme’s gem, e.g., `bundle info --path minima` for Jekyll’s default theme.

its in the docs: