The email address is defaulted from your own user settings. You can't change it. There is another workaround. You can enable business events based on alerts. You can then have an Flow in Power Automate that can act on the business event and send an email to several persons.
I'm not sure if this can be edited. But I have a workaround, if you would like to send an email to multiple users.
What you can do is create a distribution list (Maybe your IT can help you with this), where this distribution list will contain all emails you would like to send the alert to. Then, fill the field with this single "distribution list" email and alerts will be sent to all emails defined in this list.