I think it's hard to comment on food noise because we all only know our own experience. I am naturally slim and definitely experience it, so I am resentful of people suggesting things are easy for me, but then I don't know how hard it may be for some people.
For me personally there is something around habit and unconscious thoughts on what is 'normal'. This applies to portions of everything really.
I eat crisps regularly but to me, a packet is a portion. I could easily eat 3 bags but I 'know' this is excessive so I don't. Occasionally I might eat 2. I would never contemplate eating 6 bags because in my mind this would be a complete no...I wouldn't even consider this given that a bag is a portion. I don't mean this in a judgy way at all OP...just trying to explain how it 'works' for me. Interestingly I could easily, and would want to, eat one of those big bags to myself, which is much more than a couple of individual packs. But I would generally restrict to half of it because a full one just feels wrong. I think psychologically though it feels more acceptable than individual bags because it's not portioned in the same way.
I don't buy biscuits regularly but I wouldn't want or feel the need to eat an entire packet of digestives so clearly things are easier for me than for you. I would want to eat half and would probably restrict myself to a third of a pack, which would take effort. I think it depends though. Having a couple of biscuits with a cup of tea at a friend's house is a portion for me and would feel enough and in my mind is the 'right' portion. Having a pack of biscuits available for a night on my own is a different thing but in my mind, 2 is still a portion, which is why I restrict it, even though I still eat way more than 2.
A portion of sausages for me is 2 sausages. That's what I had growing up. It would never have occurred to me that others think 4 sausages is a portion before I saw it on here. Same with more than 2 wheatabix, or eating 10 fish fingers!
Edited - reading this back it sounds like I don't have food noise. I would add that I'm always hungry. I couldn't and wouldn't ever miss a meal and am genuinely constantly looking forward to food. But mine is different...I will eat my sandwich at 11am and stagger my crisps and fruit a bit around a long lunchtime to mitigate that feeling, then eat dinner early...I wouldn't eat multiple packs of something in one go (if that makes sense).