Comparisons

Sun - Earth: the average diameter of the Sun is about 1,392,000 km, almost 109 times larger than the Earth (12,742 km). This means that we could put 109 Earths side by side to match the diameter of our star.
Stephenson 2-18 - Sun: the largest known star compared to the Sun. We are talking about a radius of 2,158 solar radii (solar radius equals 696,340 km). If we were to place it at the centre of our Solar System, its photosphere would engulf the orbit of Saturn, the lord of the rings.
Ton 618 - Stephenson 2-18: the largest known black hole compared to the largest star. Ton 618 has a diameter of 2606 astronomical units (1 astronomical unit is equivalent to the distance Earth - Sun or 150 million kilometres). To give a better idea, Saturn (used as a comparison before) is 10 astronomical units away from the Sun.
We are ants in the Universe!