As @sady_rifat , @shashi_mulugu already replied there is no specific online tool available that automatically converts WCMUsePojo classes to Sling Models
However, I can provide you with a general approach and steps to manually convert WCMUsePojo classes to Sling Models:
->Start by creating a Sling Model class for each of your components. Sling Models are simple POJO classes annotated with the @Model annotation,In your Sling Model classes, annotate fields that represent the properties or resources you want to access from your components. Use annotations such as @Inject, @ValueMapValue, or @ChildResource based on the type of data you need to access.
->Identify the logic present in your WCMUsePojo classes and refactor it into the appropriate methods within the Sling Model classes.
->Replace the adaptTo and getResourceResolver calls in your WCMUsePojo classes with the corresponding Sling Model annotations and field mappings,ensure that any initialization or cleanup logic is handled appropriately in the Sling Model class.
->Sling Models support dependency injection. If your WCMUsePojo classes depend on other services or components, use @Reference annotations in the Sling Model to inject those dependencies.
Hope this helps !