Going to respectfully disagree on this. I am running in Roll20, and using the tools dynamic lighting tools in a dungeon environment have done the best exploration we've had in decades.VTTs are really bad at exploring dungeons.
The way I learnt was that you had an exploration map, drawn by a player, and you might get out minis and draw the room if necessary. You could do something similar with a VTT, have some of scaling map where a single token represents the party and then scale that down, but there seems to be no interest - it's all about the battlemaps. (And I've seen this approached used on the table top too, with the party moving through photocopied maps that get laid out as they move along)
Using dynamic lighting, characters are able to see only around 60 feet of it at a time. I even tint darkvision a red color so the vision is a little murky. I turn off "explorer mode" so the instant the characters move out of an area, it grows dark again. Torchlight isn't as good as they've thought it was either.
The players (not their characters) began to feel overwhelmed, oppressed by the magnitude of the location. They got lost. They asked me to "turn on the lights" so they could retrace their steps - and I refused. Now they are lost in a megadungeon. For the next session they are pulling out graph paper to try to record where they are going.
I think this is the best way to run a dungeon I've ever done.