About composite components
Composite components are assembled and created from existing basic
components. Essentially, you create them by selecting a group of basic components and defining
them as your own custom composite components. Typically, you use composite components when you
have a set of basic components that you want to be able to reuse as a group.
To be able to create a composite component, all the basic components must be placed into the same Flexbox. This can also be accomplished by nesting multiple Flexboxes inside a parent Flexbox, but note that the resulting composite component will include all basic components inside both Flexbox components.
Composite components can be created from scratch, saved and exported for use elsewhere, and imported from a file or from the App Builder Repository.