I've coded some myself, and have used some... but it depends on where you draw the line.

I'd consider Python's f-string syntax a DSL of sorts.

YAML might be considered a simple DSL, if you don't consider it a language/format instead. It's a bit more than 2-3 pages, but it's not hundreds of pages. And a simplified version could be constructed with <10 pages.

Similar to YAML, but for Markdown. I'd call that a DSL too, and it's even simpler than YAML.

Then, something more tiered as: CSV, JSON, TOML, INI, AsciiDoc

Once you're in the short form, it's a bit blurry what's a format, what's a DSL, and what is a language.

PS. Sorry for the late answer, I missed the direct question for a bit.