Fala rei, vê se assim funciona:

<p id="welcome"></p>

<script>
const personData = {
firstName: "Matheus",
lastName: "Araujo",
age: 18,
hairType: "Curly"
}
document.getElementById("welcome").innerHTML = "Hello, " + personData.firstName
+ "! I noticed that your hair is" + personData.hairType + "!";</script>