Eunice here from Shopify, thanks for posting, and welcome to the Community!
There isn't a way to tell if the store you linked is powered by Shopify, I recommend contacting the store owner directly to ask. Is there a particular reason why you want to know if the store is powered by Shopify? If you like the store's design or any of the store's features I'd be more than happy to give you recommendations to themes and apps that are similar.
There are some google chrome extensions that detects if a website is built with shopify. Already used one but I don't remember the name sorry.
You can do a quick search on google.
I have checked and found out that this is not a shopify websites but still not sure about this. Also, as mentioned above you can use the chrome extensions to check :- Koala Inspector chrome extension,. Try this extension.