If you have products with multiple variations, such as clothing or trainers then follow the guide below to add a Product Option to your variant products
First, go to the Inventory page
Search for or click into a product that has variations
Scroll all the way down to the bottom and click on the + New Option button
The Product Options dropdown will show at the bottom of the page.
You can then either choose an existing Product Option from the dropdown menu OR press the + ADD button, or create a new option.
Once you've added the new option click on the Edit (pencil icon) next to the variant
Under the Variant Options section, it will show you the variant options you have just entered for that specific variant.
You can enter the option value (for example, 'Black')
Then click Update.