How to Add/Update Special price of Product Magento 2?

You can Add or Update special price of the product by the SpecialPrice Interface. Catalog module contains the Special Price interface to update the special price of the product.

Base defination of the update special price of the product,
public function update(array $prices);

$prices array parameter,

Update Price Programmatically using the code snippet,

You have to create array factory of Data\SpecialPriceInterface and set SKU, Price, price_from, price_to and store id.

Output:
Boolean

Magento Commerce, you need to check Product from the Admin panel. You can see special price as Scheduled Changes.

add special price
add / update special price