Install the module composer by running composer require magesource/product-attribute-graphql:dev-main
Enable the module by running php bin/magento module:enable Magesource_ProductAttributeGraphQl
Run Magento commands by running

php bin/magento set:up;php bin/magento s:d:c;php bin/magento s:s:d -f;php bin/magento c:f

Features

Create custom product attribute and get value in product api of graph ql.

Testing

Use graphql after magento 2 store base url {Magento 2 Base Url}/graphql

Query:

{ products( filter: { sku: { eq: "{Product Sku}" } } ){ items { id sku name is_type } } }