Agree about not buying presents for friends and anyone but DC and perhaps your parents and siblings and the latter at least can be a token bottle of booze or chocolates.
It either leads to waste, becomes very transactional, where people end up sending each other links or exchanging money or vouchers or it imposes spending on non essentials on people who would be better spending their money on essentials for their own family because it creates the obligation to reciprocate.
Adults with their own money should just buy their own stuff according to their own wants, needs and budget without dragging it into Christmas gifting.
For cooking I have 2 spreadsheets, one for a simple Christmas dinner if it's just me and DP and another if we host extended family.
This includes a shopping list of what we want and need from where, eg turkey from the farm shop (we get a turkey butterfly which is a single large turkey breast which is easier to store, cook and deal with leftovers- any that's not eaten in the day or two after Christmas is sliced and frozen so can be used later).
The list is categorised into what can be bought earlier and we do the main shop before 7 am on 23/24 December so we don't have to risk online substitutions/out of stock or queue in busy supermarkets.
For wrapping paper, tags etc, along with mincemeat (I make mince pies because the pastry in shop bought ones is crap) I buy when reduced after Christmas, saves 75-90% of the cost.
As for decorations etc, again simple is best. Christmas stress seems to stem from creating a huge list of things to do, most of which are unnecessary. So to reduce this, have a think about what is essential (presents for DC, a basic turkey dinner, Christmas tree) and just do those but don't add to your stress by going to the nth degree with multiple meats, enormous piles of gifts, Elf on the Shelf, multiple Christmas trees and elaborate external decorations, Dec 1 boxes, Christmas eve boxes, hot chocolate stations, performing your Christmas to social media etc etc.