When the sun becomes a red giant it will expand to approximately its current radius.?

When the sun enters the red giant phase, it will expand to about 1.2 astronomical units (AU), which is roughly 200 times its current radius. This expansion will engulf the inner planets, potentially including Earth. The transformation is a result of changes in the sun's core and fusion processes as it exhausts its hydrogen fuel. Ultimately, this phase will lead to the sun shedding its outer layers and leaving behind a white dwarf.