The amount of time I've spent obsessing about packing organization could get me committed to an institution.
For now....for my clothes, quilt, anything "soft", it goes in separate mesh bags that are used for washing delicates, as others here have mentioned. They weigh near nothing, and you can have one for a quilt, one socks and undies, etc. All the soft mesh bags go into a large drybag and that gets stuffed to the bottom backpack. Great for getting into the banana-shaped space at the bottom of my pack created by the trampoline suspension. It avoids the weight of a bunch of drybags, and forms a nice flat 'shelf' for anything on top. You don't have to spend a lot of money. At the low end, on Aliexpress, you can get a 20 l drybag for $9. USD
If you want to go high end (and I doubt there is any practical difference), Sea to Summit have nice bags that allow you to more easily press the air out, compressing it, and they are on sale at the moment.
LIFETIME GUARANTEE. Keep your compressible gear dry- air squeezes out, water can't get in. The Evac Dry Bag is a bluesign-approved recycled 70D nylon waterproof main body fabric and a 70D eVent® waterproof but air-permeable base that allows you to push air out while still keeping your contents...
seatosummit.com
A 20 l should do. I was gifted a 35 l Sea to Summit Evac bag at Xmas, maybe larger than I need but the weight difference is near zero and it will cinch down, and it was a gift, so there.
Other than that, I have one other much smaller dry bag (8l ?) that all my electronics and miscellaneous go. I got one of those S2S ones with a window (not needed but it was on sale at the time and...I like gimmicks tbh). I have a separate drybag for First Aid, unneeded for most, but I carry Epipens and...we do 'pack our fears'. I wanted one that attracts attention in case someone else is getting it from my pack.
LIFETIME GUARANTEE. The updated Lightweight First Aid Dry Bag is the perfect way to store medical supplies and keep them dry, visible and easily accessible. An added TPU window offers excellent visibility, makes it particularly useful in group situations. Made from a bluesign® approved recycled...
seatosummit.com
Something new I am trying next trip is an ultralight toiletry bag from Decathlon, only 43 g, toiletries are bulky and are awkward to roll up, so I will hang it from the (unused) hydration tab inside the pack, so it is inside that nylon sleeve that I often seem to lose things inside to. That way it is flat and takes up less space than if I had rolled it up, and it is ready to hang up by an S-hook on a bunk bed.
This toiletry bag was designed to store and protect your belongings, and save space
www.decathlon.ca
I know this post became too long, but I did warn you that I was OCD about the packing.