html

<label>
  Allow drinks?
  <input id="allow-drinks" type="checkbox" />
</label>

<label for="drink-select">Drink selection:</label>
<select id="drink-select" disabled>
  <option value="1">Water</option>
  <option value="2">Beer</option>
  <option value="3">Pepsi</option>
  <option value="4">Whisky</option>
</select>

js

const allowDrinksCheckbox = document.getElementById("allow-drinks");
const drinkSelect = document.getElementById("drink-select");

allowDrinksCheckbox.addEventListener(
  "change",
  (event) => {
    drinkSelect.disabled = !event.target.checked;
  },
  false,
);