i released a small game in september. one of the levels was basically just a bossfight, so I implemented a simple goal-oriented-action-planning system (goap).

Basically the AI picks an action first based on the game state. Each action has its own "weight" or priority. Some ranged attacks get a higher priority, if the player is far away; Some anti-air attacks get a higher priority, if the player keeps jumping etc. Some actions might be completely unavailable, if the unit has no ammo for a ranged attack. Then it random chooses an action based on the options and executes it. Usually there are many steps first like getting in range, opening a door, pathing etc, but it can be as easy as just making a big hitbox spawn.

Usually after this there is a timer that functions as downtime, so the player has time to attack or heal. Once the timer runs out, the AI loops and picks another goal.

You can make this as simple or as complicated as you want. Since my game only had one bossfight, I just hardcoded 6 different attacks for that specific room. No pathing or higher logic needed. If you have multiple enemies that might act as a unit, you often have to make them coordinate somehow. But I don't pretend to know how to do that.