import font awesome 4.2.1 cdn code example

Example 1: bootstrap font asesome cdn

The correct one -> Give an upvote if it helps

<link
      rel="stylesheet"
      href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.14.0/css/all.min.css"
    />

Example 2: font awesome cdn

<script src="https://kit.fontawesome.com/a9545f17e8.js" crossorigin="anonymous"></script>