The breakup of the supercontinent Pangea did not significantly alter the spherical shape of the Earth. While the movement of tectonic plates and the rearrangement of continents have changed the Earth's surface over geological time, the overall shape of the planet remains largely unaffected.
The Earth's spherical shape is primarily determined by its gravitational forces and its rotation. The force of gravity acts equally in all directions, causing matter to distribute itself in a roughly spherical shape. The Earth's rotation also contributes to its spherical shape, as the centrifugal force generated by the spinning motion causes the equator to bulge slightly outward.
When Pangea began to break apart around 200 million years ago, the continental plates started to separate and drift away from each other. This process, known as plate tectonics, involves the movement of large sections of the Earth's lithosphere (the rigid outer layer) over the semi-fluid asthenosphere beneath it. The continents drifted apart and eventually formed the configuration we see today.
While the breakup of Pangea caused significant changes in the arrangement of continents, it did not alter the overall shape of the Earth. The forces responsible for maintaining the Earth's spherical shape, such as gravity and rotation, continue to shape the planet's overall form despite the dynamic nature of plate tectonics.