FWIW, here’s what I typically carry hiking solo on a cold, mid-winter day-hike of any substantial distance or elevation. It seems like a lot when listed but, like others have said, I like to carry what I need to spend the night wherever I might be. With groups, I carry mostly the same stuff.
Usually wearing:
Fleece Hat (sometimes w thin liner hat)
Gloves (waterproof, well-insulated fatties)
Long sleeve wicking tee
Fleece jacket
Waterproof parka
Mid weight Bergelene tights
Summer rain pants
Thick socks
Sock liners
Waterproof, insulated boots
Extras clothes I carry:
Balaclava
Extra long-sleeve wicking shirt
Heavy fleece pants
Extra gloves (mid weight fleece)
Extra pair warm socks
Down puffy Jacket
Gear:
Backpack
Stuff sack
Winter bivy sack
Rain cover for pack
2 Water bottles in socks or insulated sleeves
Water tabs
Headlamps (2)
Extra batteries (1-2 sets)
Whistle
Map
Compass
Lighter/Matches
First Aid Kit
Multi-tool
Straps
Food
Optional things that depend on hike:
Winter gaiters
Balaclava
20 degree sleeping bag
Goggles
Ice axe
Poles
Microspikes
Crampons
Snowshoes
Stuffed Reptar
Camera
Cell Phone
1-liter vacuum flask of hot tea
Stove
Fuel
Plastic mug
I'm sure it's not 100%, but I think it's close.
For overnights, add stove, fuel, sleeping bag (-40), full length thermarest, possibly tent, utensils.