create custom rss feed for my site?

Hi

I am using dlvr.it to autopost to my social media – it pulls from the rss feed for my site https://oldschoolnews.com/.

I would like to make a custom rss feed to only pull certain posts for the autoposting to social media.

Is there a plugin that I can use to set this up?

If there isn’t I think this would be a great addition to WP RSS Aggregator ??

The page I need help with: [log in to see the link]