If you just mean to change how combat is conducted, then that’s easy:
Turn fights into gimmicks, rather that stat stick affairs. If your players just need to be ten levels above the enemies or have equipment with stats equivalent to 10 levels above the enemies, then your combat will be “basic”. This is what every RPG (modern, indie, AAA or otherwise) fails to understand. They may add new coats of paint or different tactical options, but as long as the game is “I have more points in my stats than you do”, it all boils down to the exact same combat.
Attack, Heal, Attack, Heal, Attack, Heal.
Personally, I went in and made extensive changes to how combat works in my games. Stats matter a little, but not much overall. I removed “direct power” gain from level ups, for one. No more gaining 5 points of Attack on level up. You unlock quests and shortcuts and shops from level ups (indirect power). Stats are gained from completing quests and from equipment only. I also made it so “optimize” is a bad idea. Just because your character can wear steel plate mail, doesn’t mean its the best armor for the area (creatures faster than you, after all, will deal a ton of damage to you while you’re wearing heavy armor. Metal armor also makes you weak to all magic by a massive degree). The sword with a bajillion attack might also be useless in this area because the enemies are immune to Slashing damage. You might need to use Blunt Weapons on the skeletons and undead instead.
I removed “dedicated healer” type classes and skills. Every character is useful to every single fight so when they have to heal someone, you are making a deliberate choice to nerf damage output for a turn to avoid death. As in, your characters will all do roughly the same amount of damage to most enemies, but will do significantly more to that enemy if they’re specialized to handle that particular archetype.
Enemies “teach lessons” and Bosses are the “final quiz”. All the enemies will use tactics and states and skills on you that the boss will have, and you will learn how to handle them. Then, the boss will teach you one new mechanic, iterate on another mechanic, and use the rest of the mechanics on you from the dungeon you already learned. So, if the enemies of the dungeon teach you how to deal with poison by inflicting you with Level 1 Poison and Level 2 Poison (and the equipment in the dungeon will make you immune or resistant to only one level of those poisons, not both), the boss will have skills that inflict poison on the whole party, will have a mechanic for when you exploit its primary weakness (using fire on it, instead of using earth on it), and will add in a “stun” mechanic to the fight.
Status Effects are also deadly in my game. If you decide not to remove them immediately, then you can and sometimes will lose the fight. Poison deals as much damage to a character as being hit with a regular attack. Characters go down in about 5 hits.
I needed no plugins or anything to revamp the whole combat system. I just needed to figure out why all RPG’s play exactly the same regardless of whether they have stagger bars and other mechanics, or are bare bones. Then, I just found ways to keep combat flowing quickly while reducing the amount of times the player just hits the “attack” button instead of skills and defend and any other option.
Really helpful in general though!!! Again, thank you very much :3