To automatically generate your back-end applications, the basis is a well-defined schema and object model. The customization of the administration-generated modules are to be done mostly through configuration.
The generator.yml file is the heart of the programming of generated back-ends. It allows for the complete customization of content, features, and the look and feel of the list, new, and edit views. You can manage field labels, tooltips, filters, sort order, page size, input type, foreign relationships, custom interactions, and credentials directly in YAML, without a single line of PHP code.
If the administration generator doesn't natively support the feature you need, the partial fields and the ability to override actions provide complete extensibility. Plus, you can reuse your adaptations to the administration generator mechanisms thanks to the theme mechanisms.