It all depends on what rates did your opponent in the early streets.
It all depends on what rates did your opponent in the early streets. If your opponent raised on the flop and turn, then on the river, having the nuts, you need to bet a pot size or more. If the opponent checks on the flop and turn, then on the river you need to make a small bet, for example, half a pot or less. Still much depends on how your opponent plays, aggressively, tightly or like a fish. It is necessary to take into account all factors, in order to win from the opponent as many chips as possible and not scare him away.