Cuostmize layout

So if i wanted to make more cutomization than just a few css stylings, how would i approach that?

I want to adjust listing feeds or gd loop shortcode to similar look like this https://mylisting.27collective.net/my-city/listing-feed-types/. How is that possible?

I want to do more than just this design change so i would like to know a more general best practive way to achive this. I actually want to achieve a similar look like some of the listing themes on themeforest, but i want your plugin to back it up.

I do understand i can do a few things with parameters in the shortcodes, but that os often not enough or not possible at all to achive the result i want.

Thank you!