I want to change my Apple ID but keep my same email address

I don't understand why you want to change your Apple ID, but still end up with the same email address. You wouldn't be changing anything. The name@ part of an Apple ID is your email address. But I suppose you could change you Apple ID to something like name2@. And you could use this sort of alias set to your current email address. See Use email aliases on iCloud.com https://support.apple.com/en-nz/guide/icloud-ipad/mm6b1a490a/icloud.

If you want to create a new Apple ID, you can't use the same email address. Each Apple ID has to have it's own unique email address. You can do a name change on your existing Apple ID and you might be able to then use that address on a new ID. Apple hasn’t published any guidance for using an address again. Normally, if your e-mail address was associated with an ID in any way, for example as a Notification email address or a Rescue e-mail address, then it can't be reused with another Apple ID for approximately one year. I have also seen posts that stated Apple told them there was a 30 day waiting period before the address could be used again.  You will need to get another e-mail address to use as your Apple ID or you can try waiting 30 days to see if that works.

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.