You can choose to forward all of your new messages to another email address, or only forward certain types of messages.
You can automatically forward your messages to another address. You can choose to forward all new messages, or just certain ones.
Note: You can only set up forwarding on your computer, and not on the Gmail app.
Note: When your new messages are forwarded, messages from spam won't be included.
Note: Forwarding is not fool-proof, we recommend if at all possible to log into the main account directly if you would like to view the content of the account.
Credit to Google Support Gmail Help Article https://support.google.com/mail/answer/10957?hl=en&ref_topic=7280290. Additional information on managing Gmail forwarding is available at this address as well.