Explanation:

The example above uses Bootstrap's built-in classes along with the Font Awesome icon library for the icon:

btn: This class is used to style the button in Bootstrap.
btn-primary: This is the button color class (you can change it to any other btn-* class, like btn-secondary, btn-success, etc.).
i tag with fa-solid fa-house-chimney: This adds the icon inside the button using Font Awesome.
The custom CSS class .btn-demo (see the CSS code below) is used to make the button appear rounded.

HTML

<a href="#" class="btn btn-secondary btn-lg btn-demo" role="button"><i class="fa-solid fa-house-chimney"></i></a>

Font Awesome CSS

<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.5.2/css/all.min.css">

CSS

.btn-demo {
  width: 40px;
  height: 40px;
  font-size: 1em;
  border-radius: 100%;
  padding: 8px;
  text-align: center;
  border: 1px solid #ffffff;
  outline: 1px solid rgba(255, 255, 255, 0.60);
  outline-offset: 4px;
}

Bootstrap

Button with icon only

Explanation: