Hello, @santorinigreece .
Thank you for following up!
Though there isn’t a built-in feature for adding a slideshow on to a blog post, it may be possible to code a slideshow through HTML content with the rich text editor. However, as outlined in our design policy, customizations through the rich text editor isn’t something that we can support. If you’re not comfortable with HTML, CSS, Javascript, or Liquid, you can hire a developer from Shopify Experts to help you with this. Experts are experienced in working with custom coding and they’ll be able to create a solution for your blog posts.
Alternatively, there are a few third-party image slider apps that can install a slideshow to your blog posts. For example, Enorm Image Slider & POWR Image Slider & Carousel offers a variety of sliders that you can put on any page of your store, from hero sliders (slideshow) to carousels and much more. If you need help with one of these apps, you can always reach out to the developers through the contact information found in the Support section of their app pages.
Let me know if this is what you’re looking for?