Creation and configuration of an ad site in a specific niche

I need a classifieds site. We can use one of the many scripts for announcements that there are online (both free and premium) or even themes / plugins for Wordpress or Joomla eventually or other cms. Important is the configuration and customization. I'm still not entirely clear on the front-end and back-end functions the project should have. The thing for my part is being studied. Therefore it will be necessary to talk about it. In any case, I have already chosen the niche and purchased the host and domain. Certainly the script will have to allow the publication of free ads and allow "premium" features for paying advertisers. For example, the advertiser will be able to pay a one-off amount to be featured on all pages in a prominent box with photos, or by paying he will be able to extend the deadline of the ad three times for example and have the possibility to add more photos (7 instead of 3) or that of being able to embed videos from YouTube in the ad etc. The basic user will be able to communicate with his buyer only by email. The paid user may also have other direct contact information of the advertiser. These are the main ideas for the characteristics that the platform will have to have. Later I have more original ideas about the site and the related app that I intend to make, but I will do one thing at a time. I do not exclude a collaboration over time for future developments of the platform and the site. Based on your experience and your advice in this regard, we will certainly find a winning project to finalize.