Namecheap and other registrars provide a way to setup HTTP 301 or 302 redirects when configuring DNS. It is a nice feature since otherwise you would need to implement it yourself. See screenshot below from Namecheap DNS configuration page.
Does Google Cloud DNS offer something similar?
Firebase now has a very simple setup to achieve domain redirection, just do the following:
[Your firebase project] > Console > Hosting > Connect domain
Then it should display the following: