Based on my understanding, it will depend upon your implementation. Some of the users do not fire any Analytics server call until the cookies are accepted whereas the other fires the server call even before accepting the cookies as well. So, I will suggest you to please follow the below steps to see whether the server call is firing on the first page or not.
1. Open Incognito browser window & open the browser console by pressing F12 or Ctrl+Shift+I.
2. Go to the Network tab & use the filter as b/ss as shown below.
If you see any server call when the cookies are not accepted then bounce will be considered if the user doesn't perform any action after landing on your site.