Depends on what you mean by “explored” and how you calculate it.

Say we define “explored” as “every piece of ground within the circle made by maximum line of sight of anybody at any time”. So yeah, merely flying on a plane, you “cover” tons of ground area. According to that definition, I’d expect most of the Earth is explored. easily over 80%.

Say we defined “explored” as “appearing on Google Maps at any zoom level” then yeah, pretty much 100% of the land is already “explored”.

Say we define “explored” as “100 feet around anybody walking” then the % drops drastically.

Say we define explored as “touched the ground there with hand feet or any body part”, then we didn’t explore all that much yet. heck, there are probably a few floor tiles in your own kitchen that still wouldn’t count as having been explored by you.

If I stand in a big tower overseeing a garden, I can see the entire garden. But I don’t see what is right behind that bush over there. Does this mean I can’t have “explored” all of it no matter how hard I squint and look at the garden from my tower?

And so on.