It's not possible to outright duplicate a competitor's store, and even if it were possible, I wouldn't recommend it as you could run into potential copyright/legal issues in the future. My best piece of advice would be to create your own unique site with bits of inspiration from websites that you think are great.
If there are any particular features that you are looking for in your Shopify store, I'd be happy to help.
If there is anything else I can help you with, please let me know.
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