Good morning, @renato.moura there is a detailed step-by-step guide on how to perform this configuration in this topic here:
As for testing, what I recommend: Make the change to the payment method during a low-traffic period in your store, wait a few minutes for it to take effect, and then you can either complete a Pix transaction with a product and then cancel it, or generate a gift card for yourself worth almost the full purchase amount and pay just $0.01 via Pix to evaluate how the transaction flow worked.
Karina Mota
Field Software Engineer | VTEX