Pouring water from a height (about waist level) uses gravity to create downward force, which helps push the loosened blockage through the toilet trap.
From waist height, pour the hot water steadily into the bowl. Aim for the bottom drain hole. The force and heat can dissolve and dislodge soft clogs (toilet paper, soap scum, grease). how to unclog a toilet with hot water
If the toilet bowl is filled to the brim and looks like it might overflow, and push the flapper down to stop water from entering the bowl. If the water level is low, you can skip this step. Pouring water from a height (about waist level)