@Himanshu_Singhal,
Apache Sling Models currently includes a single exporter, using the Jackson framework, which is capable of serializing models as JSON. Adobe's new core components are built with Sling Models, meaning that if you can easily build a headless AEM solution only using the core components. If you are using Adobe's core page component, layout container, responsive grid component in editable templates, you can replace ".html" with ".model.json", and you will get a JSON representation of the page structure (resourceType & all used components); assuming that you're Apache Dispatcher module rules allow you to access .model.json. e.g: https://example.com/home.model.json
Then there's no magic happening with the Jackson Exporter; all getter properties of your Sling Models class will exposed, and serialized to JSON. This means that if you run some kind of logic in your @PostConstruct method, then set the property, the computed value will be exposed in your JSON.