You can use array_chunk to split array to group 2 item, then use foreach again
foreach (array_chunk($input_array, 2) as $group) {
// Start Group
foreach ($group as $item) {
// Item
}
// End group
}
Update with HTML
<div class="owl-carousel">
<?php foreach (array_chunk($input_array, 2) as $group) : ?>
<div class="owl-item">
<?php foreach ($group as $item) : ?>
<div class="item">
<!-- Code of item -->
</div>
<?php endforeach; ?>
</div>
<?php endforeach; ?>
</div>