If we were living on Mars, the Earth would appear smaller in the Martian sky compared to how it appears from Earth. The reason for this is primarily due to the difference in the distance between the two planets.
Mars is significantly farther away from the Sun compared to Earth. As a result, the orbital radius of Mars is larger than that of Earth. Since Earth is closer to the Sun, it would appear closer to Mars as well.
Additionally, the size of an object in the sky is determined by its angular diameter, which is the angle it subtends at the observer's location. The angular diameter of an object depends on its physical size and its distance from the observer. Since Mars is further from the Sun and therefore further from Earth, the angular diameter of the Earth would be smaller when viewed from Mars.
Therefore, if we were living on Mars, the Earth would appear smaller in the Martian sky compared to how it appears when observed from Earth.