How to return JSON resulting from POST to the front end and display the data?

Question

Although with some years of programming experience, I’m still beginner in web/mobile development. Please, patience...

I researched and tried some treatments but without success, for something that seems to me quite simple.

Goal: Return to the front end the result of the POST request executed in the back end, treat and redirect the returned information.

What I am wearing: No back-end knex usage persisting in Sqlite. No front-end React with typescript.

I am trying as follows in the back-end (synthesized code):

try {
  await trx('agendamento').insert({
                usuario_agend, data_agend, hora_agend
  });
  await trx.commit();
  return res.status(201).json(res);  // <== AQUI tento retornar o json
} catch(err) {
  await trx.rollback();
  return res.status(400).json({
    error: 'Erro inexperado ao inserir novo agendamento: ' + err
  });
};    

As can be seen, in case of success in the POST, I try to return the status and json by the instruction "Return res.status(201). json(res);". I had researched and understood that this 'res' would contain the result of "commit", however, analyzing the contents of the 'res' does not seem well.

Also, I couldn’t handle a returned json on the front end. My front-end looks like this (synthesized code):

api.post('agendamentos', {
  usuario_agend, 
  data_agend,
  hora_agend
}).then(() => {      
  //alert('Agendamento realizado com sucesso!');      
  history.push({
    pathname: '/sucessoagendamento',
    state: { detail: response.data }
  })
}).catch((error) => { 
  if (error.response){
    alert('Erro ao tentar realizar agendamento: ResponseError = ' + error.response);
  }
});

I want to replace simple commented 'Alert', I tried using 'history.push' but 'Response.data' presents me as not being valid.

So I’d like to know:

1. Which correct way to return the result of the POST method in a json to the front end in the back end?

2. How to capture the received json on the front end and redirect to a new confirmation form of the persisted data?

Could you please help me with this. All help is welcome.

Thank you.