You can change the port from settings.js to anything >1024. If you want to use something <1024 you would generally have to run Node-RED as root which is not recommended. However, you can get round that when running a service from systemd - I can't remember the details off the top of my head - it is in another post somewhere.
Alternatively, you can use a reverse proxy and hide everything behind that. That approach brings other benefits too though it does have a higher resource overhead of course.
