At this point in its life the Sun is in equilibrium: it loses mass (which would make it smaller), but this decreases its gravity and pressure (which makes it la

At this point in its life the Sun is in equilibrium: it loses mass (which would make it smaller), but this decreases its gravity and pressure (which makes it larger), and these two effects cancel out almost exactly. So the Sun will remain approximately the same size for another 5 billion years or so, until the next phase of stellar evolution.