Using this code
<button type="button" class="btn btn-primary" data-toggle="modal" data-target="#exampleModal" data-whatever="@mdo">Open modal for @mdo</button>
<button type="button" class="btn btn-primary" data-toggle="modal" data-target="#exampleModal" data-whatever="@fat">Open modal for @fat</button>
<button type="button" class="btn btn-primary" data-toggle="modal" data-target="#exampleModal" data-whatever="@getbootstrap">Open modal for @getbootstrap</button>
<div class="modal fade" id="exampleModal" tabindex="-1" role="dialog" aria-labelledby="exampleModalLabel" aria-hidden="true">
<div class="modal-dialog" role="document">
<div class="modal-content">
<div class="modal-header">
<h5 class="modal-title" id="exampleModalLabel">New message</h5>
<button type="button" class="close" data-dismiss="modal" aria-label="Close">
<span aria-hidden="true">×</span>
</button>
</div>
<div class="modal-body">
<form>
<div class="form-group">
<label for="recipient-name" class="col-form-label">Recipient:</label>
<input type="text" class="form-control" id="recipient-name">
</div>
<div class="form-group">
<label for="message-text" class="col-form-label">Message:</label>
<textarea class="form-control" id="message-text"></textarea>
</div>
</form>
</div>
<div class="modal-footer">
<button type="button" class="btn btn-secondary" data-dismiss="modal">Close</button>
<button type="button" class="btn btn-primary">Send message</button>
</div>
</div>
</div>
</div>
base.html
<!DOCTYPE html>
<html>
<head>
<title>{% block title %}{% endblock %}</title>
{% load bootstrap5 %}
{% bootstrap_css %}
{% bootstrap_javascript %}
</head>
<body>
<ul class="nav navbar-dark bg-dark">
<li class="nav-item">
<a class='nav-link text-white' href="#">M28t</a>
</li>
<li class="nav-item">
<a class='nav-link text-white' href="{% url 'login' %}">Login</a>
</li>
<li class="nav-item justify-content-center">
<a class='nav-link text-white' href="{% url 'logout' %}">Logout</a>
</li>
</ul>
{% block body %}
{% endblock body %}
</div>
</body>
</html>
template
{% extends 'base.html' %}
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
{% block body %}
<button type="button" class="btn btn-primary" data-toggle="modal" data-target="#exampleModal" data-whatever="@mdo">Open modal for @mdo</button>
<button type="button" class="btn btn-primary" data-toggle="modal" data-target="#exampleModal" data-whatever="@fat">Open modal for @fat</button>
<button type="button" class="btn btn-primary" data-toggle="modal" data-target="#exampleModal" data-whatever="@getbootstrap">Open modal for @getbootstrap</button>
<div class="modal fade" id="exampleModal" tabindex="-1" role="dialog" aria-labelledby="exampleModalLabel" aria-hidden="true">
<div class="modal-dialog" role="document">
<div class="modal-content">
<div class="modal-header">
<h5 class="modal-title" id="exampleModalLabel">New message</h5>
<button type="button" class="close" data-dismiss="modal" aria-label="Close">
<span aria-hidden="true">×</span>
</button>
</div>
<div class="modal-body">
<form>
<div class="form-group">
<label for="recipient-name" class="col-form-label">Recipient:</label>
<input type="text" class="form-control" id="recipient-name">
</div>
<div class="form-group">
<label for="message-text" class="col-form-label">Message:</label>
<textarea class="form-control" id="message-text"></textarea>
</div>
</form>
</div>
<div class="modal-footer">
<button type="button" class="btn btn-secondary" data-dismiss="modal">Close</button>
<button type="button" class="btn btn-primary">Send message</button>
</div>
</div>
</div>
</div>
{% endblock body %}
</body>
</html>
CSS view
http://127.0.0.1:8000/
https://cdn.jsdelivr.net/npm/bootstrap@5.1.3/dist/css/bootstrap.min.css
@charset "UTF-8";/*!
* Bootstrap v5.1.3 (https://getbootstrap.com/)
* Copyright 2011-2021 The Bootstrap Authors
* Copyright 2011-2021 Twitter, Inc.
* Licensed under MIT (https://github.com/twbs/bootstrap/blob/main/LICENSE)
*
/*# sourceMappingURL=bootstrap.min.css.map */