How is this site’s comments done?

Good Mornig All,

I just found this site and it looks like they have some kind of pagination going on but I am not sure how it is achieved. It is not your usual 1-5 style pagination. It shows the first 5 comments then you click a link to show all comments. How is this done please?

https://magazine.wsj.com/features/the-big-interview/miuccia-and-me/

Also, I see they have an alert box within a post show related posts from that category. I didn’t think you could automatically place any code midway into a post. How on earth did they do that?

Any hat tips greatly appreciated on this.

Thanks, as always,
Fona