First stay away from Pinterest or you will completely over estimate what is achievable with a 2 year old.
Don't expect a child that young to be interested in measuring the ingredients, making the dough, adding the colouring, rolling it out, cutting out shapes, baking/ drying, painting, stringing. Just one of those activities is a lot at that age! But you can spread out an activity over a couple of days and get a lot of mileage from it!
Strap child into high chair before beginning and wear old clothes before painting. Bath time is your follow-on activity! And possibly scrubbing paint off walls and ceiling while child naps! Just saying! Or just do the activity sitting in the bathtub!
If you want to do some kind of writing/painting on fabric bags or t-shirts, prep first by cutting a piece of cardboard to size and putting it inside the bag or tshirt. It holds it stiff which is easier to work with and it prevents colour running through to the other side. Aldi sell plain cotton totes which can be decorated for Christmas.
Finger painting is easy and much less stress than trying to manhandle a wilful toddler to make neat footprints/ thumbprints etc. The key is to choose two colours only that mix to make a third colour, e,g red and yellow (orange), blue and pink (purple) but not red and green (horse poo). You can make cards, wrapping paper, giant canvas for grandparents living room with minimum effort for you and maximum fun for child.
Cut Two quarter yards of contrasting Christmas fabric into inch squares (pref with pinking scissors) and let child make collage on plain paper with pva glue. Lovely sticky fun, bath to finish. Turn into cards or cut out into decorations
Cutting shapes out of cookies and pushing in choc chips. You could make dough in advance and freeze it until you need it as you might not have energy at Christmas. Also make salt dough now, play dough etc.
Upcycle a plain notebook with Christmas themed stickers. Pull away the piece around the stickers before you start.
Paint a huge sheet of paper green. Then fold over and over and draw one handprint to cut out a pile of hand prints (child can cut out one or two too if you like) and use to make a Christmas tree by sticking fingers down onto a triangle.
Cut out Christmas tree shape and stick onto plain white card. Decorate tree with sticky gems. Add a star to the top.
Melt choc and put in piping bag, knotted, and snipped. When cool enough for little hands let child loose with a big sheet of parchment/grease proof paper to make lots of blobs and squiggles. Then scatter sprinkles all over. Break into pieces and pop into cellophane bags and tie with ribbon. Yummy if you use nice chocolate and not the nasty cooking choc stuff.
Adapt Rice Krispie buns into Rice Krispie tray bake. Just spoon mixture into a casserole dish or baking tin and spread if spooning into cup cases is too tricky. Add some festive sprinkle stars and cut up when cool. More cellophane bags!
You might want to gather materials/ prep these now and put away for December.
If you want other Christmassy activities that aren't crafty per se:
Home made playdoh in different colours with drops of food essence added for different smells. Hide objects inside- simple things like smooth stones, Lego, a crayon or coins. Kept mine going for half an hour or more. Can be Christmassy with specific smells and colours, maybe some glitter too.
Standing at sink playing with water. If you do it on a day when you have a lot of towels to wash you can put them on the floor to catch drips and pre-soak them (efficient housekeeping yay)
Box of rice or sand or pasta with small objects hidden inside. Plastic animals or dinosaurs are great. Gets messy though
Google image search for Christmas colouring pages of current favourite cartoon.
Cut out Christmas tree from green felt and circles of coloured felt as "decorations". Velcro on back and let child decorate tree.
I've tried to think of easy low key crafts that are minimum effort for you as you'll likely be tired. The less frustratingly difficult it is for the child the longer they'll keep at it. And it builds their esteem to do it themselves rather than needing you to take over. I know it's not a very exciting list but all tried and tested!
On the other hand I might be woefully underestimating ability level. Mine have SN and youngest had exhausted frazzled mother so keeping things simple was a survival tactic 