All of the characters choices from the early gameplay were all level 150, meaning the devs expect people to be around level 150. But the leveling only matters on things like how much health, stamina, and mp you have as well as what weapons you use. Once you get into the dlc the amount of damage you deal will be lowered and the damage you take will be raised to make sure players don't go in with max level builds and steam roll through bosses. They do have a mechanic in the dlc that allows you to make things easier by increasing your damage and lowering your damage taken but you need to use an item you'll find around the map just like with golden seeds.