Adjust price based on order quantity for specific product ID

wcapbospid.php

// Adjust price based on order quantity for specific product ID by u/acephaliax
function adjust_product_price_based_on_quantity( $cart ) {
    if ( is_admin() && ! defined( 'DOING_AJAX' ) ) {
        return;
    }

    // Target product ID
    $target_product_id = 828;

    // Get the quantity of the targeted product in the cart
    $quantity = 0;
    foreach ( $cart->get_cart() as $cart_item ) {
        if ( $cart_item['product_id'] === $target_product_id ) {
            $quantity += $cart_item['quantity'];
        }
    }

    // Set price based on quantity ranges
    if ( $quantity <= 5 ) {
        $new_price = 10;
    } elseif ( $quantity <= 10 ) {
        $new_price = 15;
    } elseif ( $quantity <= 15 ) {
        $new_price = 20;
    }

    // Update the product price
    if ( $new_price ) {
        foreach ( $cart->get_cart() as $cart_item_key => $cart_item ) {
            if ( $cart_item['product_id'] === $target_product_id ) {
                $cart->cart_contents[$cart_item_key]['data']->set_price( $new_price );
            }
        }
    }
}
add_action( 'woocommerce_before_calculate_totals', 'adjust_product_price_based_on_quantity' );