Car change (and brand) during financing

Hello together, what is the procedure if you want another car of another brand during the financing? Will the car (of course with loss) be returned to the dealer and a new car made by the other dealer – or – Is there also the case that the current dealer takes the car back and takes care of the procurement of the non-branded car and adjusts the financing accordingly? So it would work if I had a brand-like wagon and during the financing (of course always with loss). Greetings