I'm afraid the other post is not strictly accurate. What you can do depends upon your age and your target age. Read this support article about how to update the birth date associated with an Apple ID: Update the birth date associated with your Apple ID - Apple Support. There's different ways to change the age on an account depending upon the age of the person, their target age, and the country's age definition of "child".
If you make a new account that: 1) Isn't the best solution. 2) You can't use an email address that Apple has seen in the past. 3) Transferring data is messy, less than satisfactory, and some things cannot be transferred at all. You will lose all past purchases unless you include the old account in a Family Sharing group (is there still room in your current family group?) If you play games, some things such as scores that are tied to a particular ID will be lost. Apple Music playlists won't transfer automatically. 4) Your new account would have to join a family group so it would be covered under any family plans.
You are much, much better off trying to deal with the incorrect age issue. Note that once you turn 18 you may find some features do not automatically activate. Restart your device.