In React Native (and also in React) you can create custom components and use them easily as much as you want in your app. You may give custom styles and values to these components by passing different values in the props of these components. However, you can not change the child components of your custom components since they are already defined.
In some cases, you may want to have containers that look alike but also have different content and differ in style. At this point, custom container components come in.