One of the things I am trying in this campaign (which I have not done in a very long time) is a true sandbox style. I am going to make all of the regions and the landmarks in the campaign before the game begins, so I don't actually know what my party will play.Design your encounters and sessions so they'll have a much harder time if the druid doesn't do their thing.
In addition to the (good!) advice others have given you, one thing to remember is to talk to the player. If you find that the druid is finding encounters and dealing with them themself instead of sharing with the party, then tell the player that they're not letting the other players shine. The game is a group game, not one where one player is off to the sides doing their own thing.A part of this too is not the druid just finding everything out, I mean the goal is to explore this crazy large new land....my fear is they feel so good at it compared to the others that they will want to just explore themselves. Now maybe they will get killed for it, maybe not....but it feels like a lot of DM time could be spent in telling them what they find, and dealing with encounters... that the other players may get bored.
So go back and look at my previous post and extrapolate while doing setting design. "There's big nasty stuff here, here, and here. There's inaccessible stuff here, here, and here."One of the things I am trying in this campaign (which I have not done in a very long time) is a true sandbox style. I am going to make all of the regions and the landmarks in the campaign before the game begins, so I don't actually know what my party will play.
So where the party goes will be completely up to them. I won't really be tailoring encounters to the party, a lot of it will be where they go, and random encounters will be rolls of the die.
A part of this too is not the druid just finding everything out, I mean the goal is to explore this crazy large new land....my fear is they feel so good at it compared to the others that they will want to just explore themselves. Now maybe they will get killed for it, maybe not....but it feels like a lot of DM time could be spent in telling them what they find, and dealing with encounters... that the other players may get bored.
This is incorrect. The party will start in an open area surrounding by a large variety of regions. Forests, jungles, open grasslands, blasted lands, the whole show.So I understand-
They're in a jungle / heavy forest to begin with.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.