To offer gift cards in different values, create a separate gift card for each value and link them together with product variations. On your website, customers see one gift card with a dropdown of values.
Before you start
Decide which values to offer, for example $50, $100, $250, $500 and $1,000, and which one should be the default. The default is the value customers see first, for example $100.
Steps
Create a gift card for each value. See How to create a gift card.
Go to Settings > Products > Gift Cards and open the gift card you want as the default, for example the $100 gift card.
Open the Product Variations section.
Add each of the other gift cards as a variation, and give each variation a name such as "$250". The steps are the same as for wines. See How to sell a wine by the glass or as a magnum (product variations).
Select Save.
What happens next
On your website, customers see the default gift card first and choose another value from the dropdown. Customers choose from the values you've set up; they can't enter their own amount.