Depends on how your blog is generated. Static generators like jekyll have plugins for this[1], but it’s also easy enough to generate it by hand with an xml template [2]. Wordpress, substack and other platforms generate it by default afaik.

[1] https://github.com/jekyll/jekyll-feed

[2] This is mine: https://github.com/facundoolano/olano.dev/blob/main/src/feed...