If you change your Apple ID, do you keep all your apps and will they update as normal?

If you change the name of the Apple ID yes.

like in:

Change your Apple ID - Apple Support

If you sign out of your Apple ID and sign in to a new Apple ID.

The apps will still be connected to the old Apple ID. And you would need that Apple ID password to update the apps.

Unless you delete and reinstall apps with the new Apple ID.

Good luck!

If you follow the steps in the article below, you retain access to all your data and previous 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.