How do I create metafields for collections?

[luspada]

I've posted this question on StackOverflow, but no answer so far: https://stackoverflow.com/questions/67196383/create-metafields-for-smart-collection-on-shopify

Any idea how to create a metafield for a (smart) collection via the API?

[Fang]

Hi, Luspada,

 You can add a Metafield app to your store, this is the app we developed, inside the app, there are 'how to use", if you need more help in developing the theme, feel free to ask me.

search Grow Force Metafields Master in the Shopify app store. 

Fang