Assuming you could somehow keep the hole open, shield it from the insane heat and pressure, and not smack into the sides, I think with a little energy loss, your body would fall toward the center of the Earth, reach maximum speed near the core, then continue upward toward the other side. On the first trip, you’d get very close to the opposite surface, but not quite make it out. Then gravity would pull you back down again. Each pass would be a little shorter than the last as energy was lost, until eventually you’d settle near the center of the Earth. The fun part is that the first trip from one side of Earth to the other would take about 42 minutes, and you’d be moving fastest at the center, roughly 5 miles per second. You’d feel weightless the whole time, because you and everything around you would be falling together. But once you passed the center, “down” would effectively flip, and gravity would start slowing you as you approached the far side.
'Earth sandwich' made by two men 20,000km apart https://www.bbc.com/news/world-asia-51171834 Tunnel to the Other Side of the Earth https://www.freemaptools.com/tunnel-to-other-side-of-the-earth.htm
Earth's underground fungal network is so massive, it would span 10% of the Milky Way, map reveals https://www.livescience.com/planet-...-span-10-percent-of-the-milky-way-map-reveals
