How do I move the discourse installed server to another server without loss?
if you’re moving to a fresh install:
Will add-ons be automatically installed as well?
this should have most of the info you need:
Themes and theme components, as well as their settings, are included in a site backup.
Plugins’ settings are stored in the backup as well, but the plugins themselves aren’t. Pay attention to this part of the link @Lilly provided: