Our documentation on gift cards outlines eligibility requirements, and how to enable the feature in your admin.
I recommend reaching out to Plus support directly for assistance with enabling these access scopes on your app.
Hey @kapil_tistabene - generally access to the Gift Card API is for Plus merchants/apps only as mentioned in our docs above. That said, another avenue you can reach out to is our Partner Support team. In your Partner Account Dashboard, there should be a little icon on the left hand side that will get you in touch with the Partner Support team directly. If you're having difficulty getting in touch with our Plus Support team, Partner Support would be the best team to provide next steps on scope access.
Hope this helps!
Al | Shopify Developer Support