If you’re looking for an example GraphQL API to play with, check out Countries.
A public GraphQL API for information about countries, continents, and languages.
curl 'https://countries.trevorblades.com/' \
-H 'Content-Type: application/json' \
-d '{"query":"{ country(code: \"BE\") { name, native, emoji, currency, languages { code, name } } }"}'
The schema’s available on the playground.