I mean by definition, or experiment if you squeeze the air out of a plastic bottle the volume would reduce. I would post a picture, but seriously pretty much every person who has every interacted with a plastic bottle would know that squeezing it would reduce the volume.

Are you a real person or are you some kind Chat GPT AI that has never actually touched a plastic bottle?

Edit: I'm tempted to post a LPT about how you shouldn't bother engaging with people who don't think the volume in a plastic bottle reduces if you squeeze the air out of it.

Edit 2: Just do the experiment, empty two bottle half way, squeeze the air out of one so there is pretty much no air/space left. Leave for a few days then see if there is any difference in fizziness.

Edit 3: Evidence the the volume reduces when you squeeze the air out https://qph.cf2.quoracdn.net/main-qimg-3d07ddd8eb1f5d84fb83848a9bdc144f.webp