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Where do you login and why do you need to set the tokens?

const data = await platform.auth().data();
data.token_type = 'bearer';
data.expire_time = 3600;
data.access_token = <access_token>;
data.refresh_token = <refresh_token>;
data.refresh_token_expires_time = 60480
platform.auth().setData(data);

You don't need to call the refresh() method. After login, if the platform instance is persisted, then call

if (await platform.loggedIn()){
  // call platform API
  const accounts = await platform.get('/restapi/v1.0/account/accountId/extension');
}else{
  console.log("Auto-login failed: BOTH TOKEN TOKENS EXPIRED")
  console.log("CAN'T REFRESH: " + e.message)
  // ask user to relogin
}

If the platform is destroyed and you want to save the tokens and reuse it after creating a new platform instance.

var tokenObj = await platform.auth().data()
var tokenStr = JSON.stringgify(tokenObj)
// stringify and safe the token string in a safe place

// then read the token and reuse it
var savedTokenObj = JSON.parse(tokenStr)
platform.auth().setData(tokenObj)
if (await this.platform.loggedIn()){
  // call platform API
  const accounts = await platform.get('/restapi/v1.0/account/accountId/extension');
}else{
  console.log("Auto-login failed: BOTH TOKEN TOKENS EXPIRED")
  console.log("CAN'T REFRESH: " + e.message)
  // ask user to relogin
}

You can implement callback functions to get notified if login, refresh succeeds or fails

platform.on(platform.events.loginSuccess, loginSuccess)
platform.on(platform.events.logoutSuccess, logoutSuccess)
platform.on(platform.events.refreshSuccess, refreshSuccess)
platform.on(platform.events.refreshError, refreshError)

Remember that after refresh successfully, you have to get the new tokens and save it for reuse