How can I test my refresh token is working with React Auth0 SDK?

No problem, happy to help!

Do you mind outlining your use case here in a bite more detail? If you are setting useRefreshTokens={true} on the the Auth0Provider then you shouldn’t need to pass any additional scope to getAccessTokenSilently.

Because silent auth is a non-interactive flow, the user will have consented to any scopes previously. Some more on this below, as well as a potential workaround to getting Auth0 to accept localhost as first party: