Is there any way I can do this through webflow without getting under the hood at differentdomain.com? I also want to shutter the hosted site at subdomain.domain.com and just have it be a redirect.
Remove the A and CNAME records for your subdomain.domain.com DNS configuration ( only ). Be careful not to damage your regular domain.com and www.domain.com DNS entries there.
Setup a redirection in your DNS provider from subdomain.domain.com to differentdomain.com how and whether you can do this depends on your provider. Cloudflare’s free DNS does this well.
Test it, verify it’s working right
Shut down your subdmain.domain.com Webflow hosting
Otherwise, its should be technically possible to just use Webflow’s wildcard redirects but you’d be paying for hosting for no reason then.