Can I change my “@icloud” e mail address?

You can retain your existing Apple ID - and all the services attached to it - and create a new email address to work with it.

One of the hidden features of an iCloud account is the possibility of creating an alias email address. Apple describes this in their support document Use email aliases in Mail on Mac (and via the Help menu option in the Mail app) where they say "An email alias is like a nickname and helps to keep your actual email address private. When you send emails using an alias, your recipients never see your actual email address."

The instructions for setting up an alias email address is on the linked page. When you have set it up go into your Mail preferences > Composing tab, then next to the statement Send new messages from: select the new email address. This will be the default setting when composing future emails. You may have to restart Mail for it to interact with iCloud.

You can also do this by signing into iCloud on the web.

You can't delete your primary email address because this is also your Apple ID, but you can choose not to use it as an email address once your alias is working.