In a large mixing bowl, beat the softened cream cheese until smooth. Add root beer, powdered sugar, and vanilla extract. Beat until well combined and creamy. Gently fold in the whipped topping until fully incorporated and smooth. Pour the mixture into the prepared graham cracker crust, spreading it evenly. Refrigerate for at least 4 hours or until set. For best results, chill overnight. Before serving, top with additional whipped cream, maraschino cherries, and crushed graham crackers or chocolate shavings if desired. Slice and enjoy this creamy, root beer-flavored treat!