Hi @cinnabams3782,
Welcome to the Auth0 Community and sorry for the late reply.
You do not need to specify the grant_type: 'refresh_token' in order to use refresh tokens in the Auth-React SDK. You have correctly requested the offline_access scope, and you also need to allow offline access from this settings page and set the useRefreshTokens: true from the Auth0 Provider, since the SDK will generate the Refresh Tokens automatically. I would recommend checking the getAccessTokenSilently documentation from the Auth0-React SDK.
I hope this helps your case, but others as well.
Best regards,
Remus