There are different time periods in economics. There is the short run and the long run. In the short run, at least one resource is fixed. It can t be negotiated or changed. In the long run, no resource is fixed.
All resources can change as the situation changes.
We also know that a firm wants to maximize profits. In the short run, the wages are fixed. If the price level turns out to be higher than anticipated, firms welcome the price increase. In this situation, the wages have been fixed so some of the cost of production is fixed, but the price they receive for their product is higher. Because TR exceed TC, firms expand their aggregate output beyond the economy s potential output.