You will know if you did well with your work because people will keep coming back for your service.
Not just twice but again and again and again.
Talking about what you can do could only help you at a point. But it will surely come when you are asked for a tangible output.
And when you finally show them your work, ensure that you put into it the best you can give while doing it.
Because all it takes is a careful eye to see through the fluff, should you choose mediocrity instead.
And then you’ll lose the job.