I have no idea what you mean. Even Storybook's front page shows a video of completely isolated components. And every single example reinforces the idea of isolated components.
What I mean is, if a component is supposed to have two children side by side with even spacing, make a test _for that parent component_ such that with arbitrary children, they end up side by side with even spacing. If your children have that logic encoded in them, then you have brittle components (the moment you move that component elsewhere, it will be applying styles for a different layout)
As if components existed in a void.