.... sun is shrinking .....
Another creationist-contrary-to-reality claim!
(Hint for they unenlightened: as the fusion reactions take place in the sun, mass is being converted to energy, and that energy eventualy works it's way to the surface where it is radiated away as light. That means the sun is losing mass slightly over time, which decreases its gravity slightly. The slight decrease in gravity over time leads to an expansion (not contraction) of the size of the sun, as there is less gravity to counteract the thermodynamic pressure of the matter comprising the sun; hence the sun expands slight as it ages, which means it is larger now than it was several billions of years ago. Additionally, the sun's energy output increases with time; this also requires the solar radius to increase, as the increased energy output in the core further offsets the tendency of the gravity of the sun to compress its contents.
IOW, for the vast majority of the lifetime of the sun, its size increases with age. Hence, a billion years ago, it was smaller, not larger, than it is now.
IOW, your interlocutor couldn't have been more wrong if he tried.
And a trillion years ago is was nothing.