Click on the menu icon > Apps > Google Workspace > Gmail.> Default Routing > Add another rule.
Under the section 1. Specify envelope recipients to match enter the email address of the account you want the rule to match.
Under 2. If the envelope recipient matches the above, do the following check the box for Change envelope recipient and enter the email address of the person who must receive those emails instead of the original recipient.
(If we are routing from an existing Alias, User or Group) Under 3. Options select Perform this action on non-recognized and recognized addresses.