How to Auto Forward email to each member in microsoft teams channel

You might be able to do something with a Power Automate flow but you shouldn't. But there is no mailbox in your tenant that is handling the channel email address so that you can setup forwarding rules as in a regular mailbox. If you somehow forward the email to multiple persons you will have many copies of it instead of keeping the discussion about the topic in the channel.

I guess that the reason is that you want the email to the channel forwarded is to notify members that there is a new email in the channel, use notifications settings in the channel instead. Or maybe you want the members to be able to answer to the email, but they can anyway in Teams click on "View original email" and that will open the mail in Outlook and they can answer.