主要思路

使用::after创建与原文本同区域位置的文字
clip-path ellipse 裁剪创建元素的可显示区域
动画执行裁剪区域
background-clip:text 以区块内的文字作为裁剪区域向
外裁剪，文字的背景即为区块的背景，文字之外的区
域都将被裁剪掉,将文字设置为 transparent

代码如下

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>focus</title>
    <style>
        html {
            font-size: 15px;
        }
        body {
            background-color: #222;
            display: flex;
            justify-content: center;
            align-items: center;
            min-height: 90vh;
        }
        h1 {
            color: #333;
            font-family: Helvetica;
            margin: 0;
            padding: 0;
            font-size: 8rem;
            letter-spacing: -0.3rem;
            position: relative;
        }

        h1::after {
            content: attr(data-spotlight);
            color: transparent;
            position: absolute;
            top: 0;
            left: 0;
            -webkit-clip-path: ellipse(100px 100px at 0% 50%);
            clip-path: ellipse(100px 100px at 0% 50%);
            animation: spotlight 5s infinite;
            background-image: url(https://images.unsplash.com/photo-1579547621869-0ddb5f237392?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=500&q=60);
            background-size: 150%;
            background-position: center center;
            -webkit-background-clip: text;
            background-clip: text;
        }

        @keyframes spotlight {
            0% {
                -webkit-clip-path: ellipse(100px 100px at 0% 50%);
                clip-path: ellipse(100px 100px at 0% 50%);
            }
            50% {
                -webkit-clip-path: ellipse(100px 100px at 100% 50%);
                clip-path: ellipse(100px 100px at 100% 50%);
            }
            100% {
                -webkit-clip-path: ellipse(100px 100px at 0% 50%);
                clip-path: ellipse(100px 100px at 0% 50%);
            }
        }
    </style>
</head>

<body>

    <h1 data-spotlight="codingchangelife">codingchangelife</h1>

</body>

</html>