Short answer
HubSpot's KB (legacy editor): redirect to a meeting scheduling page, HubSpot page or external URL, or conditionally redirect by field value, for example sending a region to its rep's meeting link. On HubSpot pages, the page editor's form module setting overrides the form's redirect.
1. The editor
A form in my demo portal.
2. Passing values
Passing submitted values into the redirect URL is a developer job using the embed code. See embedding in apps.