Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Hi GIFLY,
For technical notification e-mail address, it can be changed, you can refer to this article for more information:
Change your contact preferences for communications from Microsoft.
For the onmicrosoft.com address, you are correct - it is not feasible to change the domain, so if you wish to change your company name and by extension your default domain name, you would need to create a new tenant.
Otherwise, you can also create a custom domain and use that instead; for example: microsoft.com itself is a custom domain. You can add these kind of domains to Office 365; you can learn more here:
Add a domain and users to Office 365.
Change your email address to use your custom domain.
Regards,
Sheen