XDA supports RSS for news feed and 'latest active topics', not for specific threads.
You can, however, subscribe to any subforum or thread and you (can choose to) receieve a notification of new posts/threads, either via mail, in-site or in-app.
Once you sign in, you'll have a menu showing all subscribed threads/forums and latest messages.
Additionally, at the top there's a notification counter showing counters for PM/quotes/mentions/DevDB updates.