It's a big open world. You can just wander off and see what you find. Lots of caves and catacombs, but also some big dungeons, a couple swamps, a horrifying lake of rot, a horrible place with giant dogs and birds the birds are worse, a forest with bears, and more. At least two large areas are just completely missable/skippable.

You don't need to "follow a guide" for the bosses. People write them and they can be useful if you get stuck. But, like, you can figure it out. Old man tries to hit you with club. Don't let him do that. Then he pulls out a hammer. Don't let him hit you with that. You can look up the details for like "He takes the hammer out at 60% health, and usually throws a dagger and then jumps" but you don't really need to look that up. You just see it happen. Though sometimes the wiki is useful for like "Is this boss immune to poison?" questions