If your Components are properly defined and designed, and broken down into smaller Components. If your component composition is correct, if the data passing between these Components is correct, then your code will be Modular, Reusable, Readable, and testable.
Example: Design Components for YouTube collapsible and expanded menu. <Header component / >: maintain a state variable, and according to the state variable, you can render the collapsible left menu conditionally <Body> <left> <small menu /> <big menu> Section Header Items... </big menu> </left> <mainContent /> </Body>
Note: if the two left Components are the same, then you can use the same component, but if the two components are different, then you can create individual Components.