What will the Sun do in 5 billion years?

Could you elaborate on what astronomers predict will happen to the Sun in the next 5 billion years? Will it expand and engulf the inner planets? Will it undergo significant changes in its energy output or luminosity? Additionally, how will these potential changes affect the habitability of Earth and other planets in our solar system? It's fascinating to consider the long-term future of our celestial star, and I'm eager to learn more about its predicted evolution.