There is no way an element returns an empty bounding client rect, you just need to look a bit harder.

For example.com:

cy.visit('https://example.com');

cy.get('h1')
  .first()
  .then(($target) => {
    let coordsDrop = $target[0].getBoundingClientRect();
    cy.log('coordsDrop', coordsDrop);
    console.log('coordsDrop', coordsDrop);
  })

The log:

Click the log entry:

or use consolg.log(coords)