Bootstrap CSS class .order-sm-0

    <div class="d-flex flex-row mb-3">
        <div class="p-2 bg-info">Flex item 1</div>
        <div class="p-2 order-sm-0 bg-primary">Flex item 2</div>
        <div class="p-2 bg-info">Flex item 3</div>
    </div>