This might be completely impossible but heck I'll suggest anyway. Flame attacks scorch the ground and can deal very small DOT for like 5 seconds when people stand on it. Explosions leave dips in the ground OR rocks around the move that can be used to block projectiles or stand on. Water breathing will soak a person, making thunder more effective (longer stun time or more DMG, which ever feels less broken). Fire could then evaporate the soak status effect,and water can get rid of scorched ground, making those two styles not mesh so well. As for special effects on arts... Honestly everything I know about demon slayer comes from dsrpg2, I don't even like the anime... But to add more interactive terrain/effects could add to the emersive aspect of the game.
Also breakable buildings/trees (I know that's a stretch but I already made it this far) that respawn in a set amount of time.
EDIT: After reading another suggestion that wants the opposite of this, I understand NOT wanting these kinds of things in a game to avoid them being out of balance. To counter that from happening... I suggest just not having any of this stuff apply to competitive modes like arena. And if you really want to take it a step further, you can have "dry zones" where status effects just don't occur on the main map. Popular towns are good spots for these dry zones.

Milky Guy 🥛🍼#3469 You’ve Reached Level 15