According to the search results, it is recommended to be at least level 5 before attempting to travel through the Mountain Pass in Baldurs Gate 3. The game warns players not to go there until they reach level 5, which is a huge buff for just about every class. Level 5 is also when players unlock level three spells and subclasses among their companions, if possible. While it is possible to find the route to be viable while being on level 4, it is recommended to grind your way to the upper level. The enemies in the Mountain Pass are pretty difficult, and they are all level 6 or higher, so attempting to go through the area at level 3 would be very challenging.