Add any of the below mentioned modifier classes to change the appearance of a badge.
                                          
  <span class="badge bg-primary">Primary</span>
  <span class="badge bg-secondary">Secondary</span>
  <span class="badge bg-success">Success</span>
  <span class="badge bg-danger">Danger</span>
  <span class="badge bg-warning text-dark">Warning</span>
  <span class="badge bg-info text-dark">Info</span>
  <span class="badge bg-light text-dark">Light</span>
  <span class="badge bg-dark">Dark</span> 
                                      
                                  
                          Use bg-opacity-10 classes.
                        
                                            
    <span class="badge bg-primary bg-opacity-10 text-primary">Primary</span>
    <span class="badge bg-secondary bg-opacity-10 text-secondary">Secondary</span>
    <span class="badge bg-success bg-opacity-10 text-success">Success</span>
    <span class="badge bg-danger bg-opacity-10 text-danger">Danger</span>
    <span class="badge bg-warning bg-opacity-10 text-warning">Warning</span>
    <span class="badge bg-info bg-opacity-10 text-info">Info</span>
    <span class="badge bg-dark bg-opacity-10 text-dark">Dark</span> 
                                        
                                    
                        Use the .badge-pill modifier class to make badges more rounded (with a larger border-radius and additional horizontal code).
                      
                                          
  <span class="badge rounded-pill bg-primary">Primary</span>
  <span class="badge rounded-pill bg-secondary">Secondary</span>
  <span class="badge rounded-pill bg-success">Success</span>
  <span class="badge rounded-pill bg-danger">Danger</span>
  <span class="badge rounded-pill bg-warning text-dark">Warning</span>
  <span class="badge rounded-pill bg-info text-dark">Info</span>
  <span class="badge rounded-pill bg-light text-dark">Light</span>
  <span class="badge rounded-pill bg-dark">Dark</span> 
                                      
                                  
                        Badges scale to match the size of the immediate parent element by using relative font sizing and em units.
                      
                                          
  <!-- start avatar-->
  <h1>Example heading <span class="badge bg-secondary">New</span></h1>
  <h2>Example heading <span class="badge bg-secondary">New</span></h2>
  <h3>Example heading <span class="badge bg-secondary">New</span></h3>
  <h4>Example heading <span class="badge bg-secondary">New</span></h4>
  <h5>Example heading <span class="badge bg-secondary">New</span></h5>
  <h6>Example heading <span class="badge bg-secondary">New</span></h6>
  <!-- end avatar-->  
                                      
                                  Badges can be used as part of links or buttons to provide a counter.
                                          
  <button type="button" class="btn btn-primary">
    Notifications <span class="badge bg-secondary">4</span>
  </button>
  <button type="button" class="btn btn-primary position-relative">
    Inbox
    <span class="position-absolute top-0 start-100 translate-middle badge rounded-pill bg-danger">
      99+
      <span class="visually-hidden">unread messages</span>
    </span>
  </button>
  <button type="button" class="btn btn-primary position-relative">
    Profile
    <span class="position-absolute top-0 start-100 translate-middle p-2 bg-danger border border-light rounded-circle">
      <span class="visually-hidden">New alerts</span>
    </span>
  </button>