DIsplay text and image for newsletter list page

I am using contao newsletter module. Currently for listing newsletters, we use newsletter list module. But it shows only date, time, newsletter subject in the frontend. I need to have text and image along with this?

So what I am planning is to extend the newsletterlist module in system/extended_newsletter/modules/ModuleNewsletterList.php. Is this the correct way?

While debugging, I am not getting the text field value (on extending this module). What should I do to get the text and image fields also, for the newsletter list page? Can you explain with the code?

I debugged and was able to display the text and image.
Thank you.