What do you mean with "check the backend"? You can e.g. do assertions on HTTP-responses coming from the backend - is this what you head in mind?

If you want to test the backend on its own, I personally would recommend using a different framework than cypress (or a different framework than the one being used for frontend e2e testing in general). Otherwise you risk that people conflate these two things and start "testing the backend" in e2e-tests for the frontend, which are super slow.