You can add tier prices from admin panel.
Navigate to Admin Panel > Catalog > Product > Add/Edit Product >
Advance Pricing (below price input box) > Tier Price > Add
Magento shows tier price in product view page by default.
If you want to show tier price in product list page then put below code in your list.phtml file where you want to show tier price.
if($_product->getTierPrice()){
$tier_price = $_product->getTierPrice();
foreach ($tier_price as $key => $value) {
$qty = (int)$value['price_qty'];
$price = $value['price'];
$formattedPrice = $this->helper('Magento\Framework\Pricing\Helper\Data')->currency(number_format($price, 2), true, false);
$savePercentageFormat = ceil(100 - ( (100 / $_product->getPrice())* $value['price']) ) ."%";
echo "Buy $qty for ".$formattedPrice." each and save ".$savePercentageFormat;
echo "<br>";
}
}