[id].tsx

const Doggo: NextPage = ({ dog }) => {
  ...
};

// This function gets called at build time
export const getStaticProps: GetStaticProps = async () => {
  // Call an external API endpoint to get a dog
  const res = await fetch("https://.../dogs/a-doggo");
  const dog = await res.json();

  // By returning { props: { dog } }, the Doggo component
  // will receive `dog` as a prop at build time
  return {
    props: {
      dog,
    },
  };
}

export default Doggo;