Does anyone know where i'm going wrong? thanks in advance

Tell us what’s happening:

Your code so far


<style>
  .red-text {
    color: red;
      <p>font-text: 16px </p>;

  }
</style>

<h2 class="red-text">CatPhotoApp</h2>
<main>
  <p class="red-text">Click here to view more <a href="#">cat photos</a>.</p>
  
  <a href="#"><img src="https://bit.ly/fcc-relaxing-cat" alt="A cute orange cat lying on its back."></a>
  
  <div>
    <p>Things cats love:</p>
    <ul>
      <li>cat nip</li>
      <li>laser pointers</li>
      <li>lasagna</li>
    </ul>
    <p>Top 3 things cats hate:</p>
    <ol>
      <li>flea treatment</li>
      <li>thunder</li>
      <li>other cats</li>
    </ol>
  </div>
  
  <form action="/submit-cat-photo">
    <label><input type="radio" name="indoor-outdoor" checked> Indoor</label>
    <label><input type="radio" name="indoor-outdoor"> Outdoor</label><br>
    <label><input type="checkbox" name="personality" checked> Loving</label>
    <label><input type="checkbox" name="personality"> Lazy</label>
    <label><input type="checkbox" name="personality"> Energetic</label><br>
    <input type="text" placeholder="cat photo URL" required>
    <button type="submit">Submit</button>
  </form>
</main>

Your browser information:

User Agent is: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.79 Safari/537.36.

Link to the challenge:
https://learn.freecodecamp.org/responsive-web-design/basic-css/change-the-font-size-of-an-element

You are trying to style the “p” element inside another class with the wrong format.
first open the entry for “p” elements after the class you were writing then style the font-size there, like this:

<style>
  .red-text {
    color: red;
  }
//open the entry for p elements then style them
  p {                           
    font-size: 16px;  
  }
</style>

of course!, thanks !