there is no confirmed evidence of any planets in our solar system or any known exoplanets having mountains taller than Earth's tallest mountain, Mount Everest. Mount Everest stands at approximately 8,848 meters (29,029 feet) above sea level.
However, it's important to note that our understanding of exoplanets is still limited, and new discoveries are continually being made. With advancements in technology and future exploration, it is possible that we may find planets with mountains exceeding the height of Mount Everest or even other geological features that surpass Earth's. But currently, we have not observed such mountains on any known planet.