While you won't get a fully-functioning dungeon with doors, traps, light sources, etc. by searching online for an image, you can get all that with a little extra effort. With a Base subscription (free), you can create areas of the map which are completely black to your players (fog of war), and erase them manually as your players progress, open doors, etc. You can move things between the GM, Object, and Map layers as needed, such as when a player steps on a hidden pit trap, moving a "pit trap" image from the GM layer (hidden to players) to the map layer (visible to players and underneath all of their tokens). A Supporter subscription ($5/mo or $50/yr) gets you access to dynamic lighting, which you can pair with or use instead of the fog of war. Dynamic lighting allows you to set up light-blocking walls (on a layer above the GM layer), and assign light sources to tokens. Depending on settings, players will be able to see the results of the lights intersecting with the walls, revealing the map as they move around. A Mentor subscription ($10/mo or $100/yr) gets you access to the API system, a JavaScript library which you can use to add many, many features to your game. This could be anything from new chat commands to automation (such as automatically revealing that pit trap when the player moves) and more. If you are not a programmer, there are many people in the API forum who have already written scripts you can use, or are willing to help you write new scripts for your needs.
