If the clog is caused by organic waste or excess toilet paper, heat and lubrication might be the answer. This is the gentlest method and should be your next attempt after the plunger fails.
Wait, didn't the plunger already fail? You might just be using it wrong. Many people push the plunger in and out frantically, but the suction is created on the pull , not the push. toilet is clogged plunger not working
If the water in the bowl is actively rising, remove the porcelain tank lid, reach inside, and press the rubber flapper valve down firmly over the bottom drain hole. This immediately stops water from entering the bowl. If the clog is caused by organic waste