Special Price is called as a promtional campaign you will give to shoppers wwithin an exact time. The special price is shown both on the catalog page and product detail page while the ordinary price is grayed out, both of them is liked by word “was” like $30.00 was $36.00.
From Magento 2 settings, you can get the special price configuration in the Advanced Settings of the individual product. In that, you only need to enter the number for the discounted price and the active time to apply. As you config, the special price is applied immediately.
Editlink on the Product Management.
Advanced Settings > Advanced Pricing.
Special Price From Dateand
Special Price To Date. You can type manually or click on
Calendaricon to choose the relevant date.
Savebutton to finish.
Reference: Magento 2 user guide
It comes to the end of tutorial: How to Setup Special Price in Magento 2.