How can I stop receiving unwanted emails from stores and advertisement?

Unfortunately, you have to block them one at a time. And that is not always effective because many of these spam senders use many different email addresses. Instructions are below. But one warning, do not tap Unsubscribe. That just let the spammer know your address is live. They wil likely sell it. Others here may have more tips.

Block phone numbers, contacts, and emails on your iPhone or iPad - Apple Support