A sale price set for a product variant overrides any other possible group and single product discounts that may apply to the parent product.
The below instructions presume that product variants for which you need to set sale prices have already been created as described in the section Product Variants.
To set a sale price for a product variant:
Navigate to the product listing page in your store's Admin area (Catalog -> Products), find the product to configure a sale price, and click on the product name to open the product details for editing.
On the product details page, click the Variants tab to access the product variants.
Use the Sale column to configure sale prices for the product variants:
You can set the sale price either in the absolute value of the store's currency or as a percentage of the variant's base price as specified in the main Price field.
Click Save changes to save your changes.
For products with product variants, the product price shown on the storefront on product listing pages and the details page of the product itself when you first access it will reflect the sale discount set for the default product variant. The sale discounts configured for the other variants of the same product (if any) will be displayed when viewing the respective product variants on the product details page.
Storefront product listing page
Storefront product details page. Default variant.
Storefront product details page. Other variants.