option1.yaml

codegen/_graphql.tsx:
  plugins:
    - 'typescript'
    - 'typescript-operations'
    - 'typescript-resolvers':
        avoidOptionals: false
    - 'typescript-react-apollo'
  config:
    withHooks: true
    hooksImportFrom: '@apollo/react-hooks'
    avoidOptionals: true
_schema.graphql:
  plugins:
    - schema-ast

option2.yaml

codegen/_graphql.tsx:
  plugins:
    - 'typescript':
        avoidOptionals: true
    - 'typescript-operations':
        avoidOptionals: true
    - 'typescript-resolvers':
        avoidOptionals: false
    - 'typescript-react-apollo':
        avoidOptionals: true
        withHooks: true
        hooksImportFrom: '@apollo/react-hooks'
_schema.graphql:
  plugins:
    - schema-ast