Live Demo: Bootstrap Auto-layout Columns

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Bootstrap Auto-layout Columns</title>
<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/css/bootstrap.min.css" rel="stylesheet">
<script src="https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/js/bootstrap.bundle.min.js"></script>
<style>
    /* Some custom styles to beautify this example */
    .row{     
        margin-top: 1rem;
        background: #dbdfe5;
    }
    .col{
        padding: 10px 15px;
        background: #abb1b8;
        border: 1px solid rgba(0,0,0,0.5)
    }
</style>
</head>
<body>
<div class="container">
    
    <div class="row">
        <div class="col">.col</div>
        <div class="col">.col</div>
    </div>

<div class="row">
        <div class="col">.col</div>
        <div class="col">.col</div>
        <div class="col">.col</div>
    </div>
</div>
</body>
</html>