> How big would it have to be in order to get a Google Earth resolution on a planet many light years away?

If you're ok to settle for a lower resolution, then a couple hundred astronomical units. Surprisingly, this may actually be feasible by using the sun as a gravitational lens. It would just take a lot of time to get the light collecting instrument in position at the focal point.

https://news.stanford.edu/press-releases/2022/05/02/gravity-...

Edit: the Stanford press release says that without exploiting gravitational lensing, "we would need a telescope 20 times wider than the Earth".