As rasberrybaret above me mentionend. There are various triggers & event flags. In your main hub area there are white lanterns above the "door". The more of them light up the more progess is made(by killing boss enemies). Tho worth to mention as well resting at bornfires triggers progess etc. in new areas.Are there missable things like in BS1? I mean things getting blocked by simply progressing.
Depending on your route good or really bad things can happen.
BSI in that regard was a lot more forgiving if you fucked up some stuff. BSII is harsher on you overall.