Вот так?:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<div class="bg">
<div class="inner"><h1>Heading</h1><p>Lorem ipsum dolor sit amet consectetur adipisicing elit. Odio, perspiciatis nobis tempore deserunt iusto delectus alias sunt at quo aut molestias possimus cum numquam rerum pariatur quis ab ut quasi!</p></div>
</div>
</body>
<style>
.bg{
width: 900px;
display: flex;
justify-content: center;
align-items: center;
height: 600px;
background: url(https://img.freepik.com/free-vector/spring-landscape-scene_52683-56331.jpg?t=st=1676042552~exp=1676043152~hmac=a344e4dbe3e47487bf10ec2aa6bef3ea1bc3b4e23a68ef595ea082d4ea17755f);
background-repeat: no-repeat;
background-size: cover;
}
.inner{
width: 100%;
color: white;
height: 100%;
display: flex;
justify-content: center;
flex-direction: column;
align-items: center;
/*Затемнение*/ backdrop-filter: brightness(50%);
}
</style>
</html>
