In addition to a fixed price, you can also store a campaign or special price in the product settings (e.g. for sales, sales, etc.). As long as this option is activated, the product will be sold through the shop at the reduced price. If you deactivate it, the normal price will be shown again.
To do this, select the menu item “Products” and open the desired item. Below the description field there is a checkbox where you can activate the special price and enter your desired special price.