Welcome to Shopify Community. My name is Olivia and I work here.
Thanks for sharing your post with our network. While it's tough to say what app or customizations these sites have made to their FAQ page, I have found the perfect solution for you to implement something similar in your own store.
Check out this awesome blog post on The FAQ Page: Why you need it, how to build one, and 10 examples.
Once you open up that link with me you will find several app recommendations that include:
Make sure to read the full blog post to see all the great examples that each app can help create on your site.
I trust you will find this information helpful, but don't hesitate to reach back out if you have further questions.
Besides those apps for FAQ as Olivia suggesteou can consider using page builder app like PageFly to build your own FAQ page as well. PageFly has these Accordion elements with collapsible headings where you can freely add to any page type, right into your product page, not only just a separate FAQ page.
Hope you find that helpful!
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