I would like to ask my expert friends, can the store image design be protected?

What they did has constituted infringement and unfair competition. If you can prove that your store was opened before his, you can win the lawsuit

You can apply for an appearance patent for store image design. You can also write down the decoration features, service features, etc. of your store, attach pictures, and apply for copyright registration. Consultation hotline: 020-85546474