Technically, a 301 permanent redirect (which is permanent), is an HTTP status code, meaning it is sent to a browser from an HTTP server.
I still haven’t gotten around to using it, but there is a hidden feature in MiaB to support custom nginx configurations for each domain. It makes use of either .conf files or custom.yaml or something in /home/user-data/www/, and you could use that to create a redirect or return configuration.
I probably never use such features because I have a different server I would set up the A record to point at and configure the redirect there.
You also can use a simple HTML page that redirects, but it is just a refresh to a different URL, not a 301 status code.