https://jsfiddle.net/yarkov_aleksei/djcm92n0/
<select id="fonts">
<option value="" disabled selected>Choose font</option>
<option id="cursive">cursive</option>
<option id="fantasy">fantasy</option>
<option id="monospace">monospace</option>
<option id="sens">sens-serif</option>
</select>
<div id="one">
Lorem ipsum dolor sit amet, consectetur adipisicing elit. Recusandae, assumenda deserunt perferendis natus, modi eligendi vel facere qui odio corrupti earum quam porro nemo impedit vitae autem eaque, accusamus et?
</div>
let one = document.getElementById("one");
let fonts = document.getElementById("fonts");
fonts.addEventListener('change', (e) => {
one.style.fontFamily=e.target.value;
})