Hi and welcome to the community. 
Are you talking about the Top Sites displayed in a New Tab Page? You can have up to 12 if your go to the Customize Dashboard and change the setting to Favorites.
There is a feature request to add more. You might want to go vote there! I’ve read in various topics that Brave staff do browse the Feature Request and Feedback categories.
If that is not what you are talking about, could you explain exactly where this is accessed?