Needing to change Apple ID

You can do a name change to your Apple ID and still retain your data and purchases.

Note the restrictions in the article.

Apple ID Name Change

 What to do after you change your Apple ID or password - Apple Support     I suggest doing this before you change your Apple ID or password.

You can't. Everything is tied to your Apple ID. Why do you need to change it? You actually cannot "change" and Apple ID. You would simply create a new one. You could then stop using the old one or you could delete it.