Per the specs on the dell website, it's a milled aluminum chassis. Guess that could technically mean there's plastic somewhere, but they seem to be selling the fact it's not plastic.
Through some kind of engineering magic, they've been able to make it out of thin aluminum while still retaining the creaky plastic feeling Dell is known for.
The top shell and the bottom shell are thin aluminum but the rest of the laptop is plastic. The bottom assembly is a plastic body screwed into a thin aluminum shell. Unfortunately I don’t have a link but there are reviews on YouTube where people subject it to the “twist test” and the laptop body creaks and visibly twists under light manual force.