The Bootstrap buttons are aligned to the center using the CSS properties 'display: flex' and 'justify-content: center'.
<div class="demo-justify-content-center">
<button class="btn btn-outline-secondary" type="button">Button</button>
<button class="btn btn-outline-secondary" type="button">Button</button>
<button class="btn btn-outline-secondary" type="button">Button</button>
</div>
.demo-justify-content-center {
display: flex;
flex-direction: row;
gap: 20px;
justify-content: center
}