I have a card that says "whenever Karplusan Hound attacks, attacks, if you control a Chandra planeswalker, this creature deals 2 damage to any target."
Does this mean I can target a planeswalker?
Yes, any target includes planewalkers
The wording was a relatively recent change. Previously, very few damage-dealing spells and abilities could target planeswalkers directly. Instead, you redirected damage from targeted players to one of their planeswalkers at resolution.
114.4. Some spells and abilities that refer to damage require “any target,” “another target,” “two targets,” or similar rather than “target [something].” These targets may be creatures, players, or planeswalkers. Other game objects, such as noncreature artifacts or spells, can’t be chosen.