Cookie policy is required by many countries. Not having one can cause issues. Having said that, I think the balloon is to intrusive. There are other less intrusive cookie alerts.
https://www.cookielaw.org/the-cookie-law/
The Cookie Law Explained
The Cookie Law is a piece of privacy legislation that requires websites to get consent from visitors to store or retrieve any information on a computer, smartphone or tablet.
It was designed to protect online privacy, by making consumers aware of how information about them is collected and used online, and give them a choice to allow it or not.