It's not that relevant, it's just that this boss, later in the game, will be a regular enemy, so the regular ones should respawn whenever their initial position is on-screen (which is already set up) but the boss one should only be fought once, so I created a boolean only that instance has true, but don't know how to make it so enemies with that set to true won't be recreated
I dont understand why the regular enemies that are not bosses will have the Boolean true. Normally you will set only the one who is boss to true after all that's why you added the boolean to identify who is the boss, then when the user completes the boss just turn the boolean off for that boss so it becomes regular like the other ones.
Though you will have to keep the Boss info if it's (completed or not) saved in a "Local storage" to keep up to date with the progress because the objects will always load their default values like (booleans, instance variables, etc...) unless you load from "System Save" which it will save the current state of all the objects on the game including booleans, etc...
If you dont use the "System save" to save and load the Game then I will recommend you use (local storage + the Boolean you have)
For example:
Let's say is Boss1
1-At the start of the layout loads the info from local storage into a variable or you could have a dictionary holding all the info for all the bosses and just load the whole dictionary from local storage.
2-To spawn the enemies you can do:
If Boss Boolean is false: ------------- Spawn as a regular enemy
Else: Is boss completed: ------------- Spawn as a regular enemy
Else: ------------- Spawn as Boss