behaviorBootstrap 5 Checks and radios Default (stacked) is used to create a stack of checks and radios as a list. To create a stack we need to put the checks and radios normally one by one that will create stacks it's the default behaviour of Bootstrap 5 Checks and radios.
Bootstrap 5 Checks and radios Default (stacked) Class: There is no pre-defined class to create the stacks we just need to put multiple checks and radios one by one that will stack them up.
Syntax:
<div class="form-check">
<input class="form-check-input"
type="checkbox" value="">
<label class="form-check-label" for="inputID">
...
</label>
</div>
Below examples illustrate the Bootstrap 5 Checks and radios Default (stacked):
Example 1: In this example, we will learn about Stacked Checkboxes.
<!DOCTYPE html>
<html>
<head>
<!-- Bootstrap CDN -->
<link href=
"https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/css/bootstrap.min.css"
rel="stylesheet"
integrity=
"sha384-EVSTQN3/azprG1Anm3QDgpJLIm9Nao0Yz1ztcQTwFspd3yD65VohhpuuCOmLASjC"
crossorigin="anonymous">
<script src=
"https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/js/bootstrap.bundle.min.js"
integrity=
"sha384-MrcW6ZMFYlzcLA8Nl+NtUVF0sA7MsXsP1UyJoMp4YLEuNSfAP+JcXn/tWtIaxVXM"
crossorigin="anonymous">
</script>
</head>
<body class="m-2">
<div>
<h1 class="text-success">
GeeksforGeeks
</h1>
<h2> Checks and radios Default (stacked)</h2>
<div class="form-check">
<input class="form-check-input"
type="checkbox">
<label class="form-check-label">
Queue
</label>
</div>
<div class="form-check">
<input class="form-check-input"
type="checkbox"
disabled>
<label class="form-check-label">
Stack
</label>
</div>
<div class="form-check">
<input class="form-check-input"
type="checkbox">
<label class="form-check-label">
Linked List
</label>
</div>
</div>
</body>
</html>
Output:

Example 2: In this example, we will learn about Stacked Radio Buttons.
<!DOCTYPE html>
<html>
<head>
<!-- Bootstrap CDN -->
<link href=
"https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/css/bootstrap.min.css"
rel="stylesheet"
integrity=
"sha384-EVSTQN3/azprG1Anm3QDgpJLIm9Nao0Yz1ztcQTwFspd3yD65VohhpuuCOmLASjC"
crossorigin="anonymous">
<script src=
"https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/js/bootstrap.bundle.min.js"
integrity=
"sha384-MrcW6ZMFYlzcLA8Nl+NtUVF0sA7MsXsP1UyJoMp4YLEuNSfAP+JcXn/tWtIaxVXM"
crossorigin="anonymous">
</script>
</head>
<body class="m-2">
<div>
<h1 class="text-success">
GeeksforGeeks
</h1>
<h2>Checks and radios Default (stacked)</h2>
<div class="form-check">
<input class="form-check-input"
type="radio">
<label class="form-check-label">
Stack
</label>
</div>
<div class="form-check">
<input class="form-check-input"
type="radio">
<label class="form-check-label">
Queue
</label>
</div>
<div class="form-check">
<input class="form-check-input"
type="radio" disabled>
<label class="form-check-label">
Linked List
</label>
</div>
</div>
</body>
</html>
Output:

Reference: https://getbootstrap.com/docs/5.0/forms/checks-radios/#default-stacked