This depends on the platform. Please, follow the link to the help article for each platform.
Platforms tend to create profiles based on user searches and data providers. This results in many unclaimed profiles across the platforms. These profiles my cause confusion between users as they don't usually include correct information. However, users can leave reviews to these uncontrolled profiles but the business owner has no possibility to reply before first taking over that profile.
We recommend you to claim all profiles for your business locations. Have a look these links to know how to claim profiles unclaimed on each platform.