When the player pasts a certain point , I want it to restart at the player start location, I have no ai so the level itself doesn’t need to reset, I could just use a box trigger but is there a way to use the kill z for future projects?

You could use a Kill Z volume if you wanted and then set up a system when the player gets destroyed, it activates a custom event to respawn them wherever you want.

I created a video for this type of thing recently actually.