I want to make a user script that changes the max value of an input form

<div>
  <label>Time limit (in minutes, max 120)</label>
  <input type="number" name="max_time" value="60" min="1" max="120" required="">
</div>

The value I'm after is 120, and the userscript should only be able to modify that value.

The question When to use setAttribute vs .attribute= in JavaScript? is not useful here since my question is about modifying html with user scripts.