SuperTokens is an open source authentication solution offering features like: Different types of login: Email / password, Passwordless (OTP or Magic link based).

SuperTokens.com

can I override the `getUserById` function?

Yea. You should be able to override this too

I can see from here too 
https://supertokens.com/docs/nodejs/modules/recipe_thirdpartyemailpassword.html#getUserById-1

but I don't know where it should be defined

Im not sure I understand what you mean by how it should be defined

```
ThirdPartyEmailPassword.init({
    override: {
        functions: (oI) => {
            return {
                ...oI,
                getUserById: async function (input) {
                    // TODO..
                }
            }
        }
    }
})
```

<@498057949541826571> this returns an empty object in react native
`let accessTokenPayload = await SuperTokens.getAccessTokenPayloadSecurely();`

then it probably means that the access token payload is empty. Are you adding something to it on the backend?

See this: https://supertokens.com/docs/thirdpartyemailpassword/common-customizations/sessions/new-session