To connect to a database using ngrok, you will need to use a TCP endpoint. Once you have your database up and running, you should be able to remotely connect to it using an ngrok TCP endpoint and the default port of 3306. 
ngrok tcp 3306
TCP endpoints are only available on a free plan after adding a valid payment method to your account.
You can then use the ngrok TCP address and port for any tool that you’d like to use to remotely connect to your database. The following guides offer step-by-step instructions for configuring site-to-site connectivity with your database.