While dog parks can be a ton of fun, they are very unpredictable and can expose your dog (and other dogs) to dangerous situations (like fights). We do not recommend visiting dog parks until you know your dog's personality, are fully aware of their stress signals, and feel confident that they don't pose a risk to themselves or other dogs.
To increase your control of the situation, work on the “come” command with your dog. This will help you get him if/when it’s time to leave the dog run.