The Duolingo English Test ends with an interview and a writing sample that are sent to the institutions you apply to, alongside your score. They are not scored by the algorithm. An admissions officer watches and reads them.
That changes what you should do with them. The scored items reward speed and accuracy; these two reward being a person the reader can picture on their campus.
The writing sample. You choose a prompt and write for five minutes. Aim for a complete short answer rather than an ambitious unfinished one: an introduction, two developed points, a closing line. Type it as a paragraph structure, not one block — a wall of text is read less carefully by everyone.
The video interview. You speak for one to three minutes on a prompt. Look at the camera, not at yourself. Speak at your normal pace. A rehearsed monologue delivered flawlessly is less persuasive than a slightly imperfect answer that sounds like you thinking.
Write and speak about something real. The prompts are open and general — describe a place, an experience, a choice you made. A specific answer about your own city, your own project, your own family is memorable; a generic answer about "the importance of education" is not, and an admissions officer has read a thousand of those.
Practicalities. Both are one take. Check your camera framing and your room's light before you start the test, not during it — your face must be visible and forward for the whole hour anyway under the proctoring rules, and a badly lit sample is the one an officer remembers for the wrong reason.