My DD (now 12) has always made cookies to put onSanta’s plate on Christmas Eve. When she was 12 months, this mostly consisted of whisking the egg, stirring flour and spices together after sifting, and making a mess rolling out some dough. The following year, she was able to do more and her rolling out and cutting with cookie cutters was much better.
Nowadays we do a “slice and bake” type of dough rather than a roll out and cut with shaped cutters type. We like them occasionally anyway, so I make sure to make a batch in November sometime and freeze half the log. It lasts ages in the freezer - but it gives the option on Christmas Eve to just slice and bake if time/energy is against us. Or we can do a batch from scratch as they will be eaten over the next few days anyway, if we have plenty of time and want to fill it.
Can you go for a walk in a local park or woods or beach and see what the animals are doing? Any signs of tracks or animals themselves, or are they all like the bear in the ad - having a long winter snooze?
Or maybe keep the job of wrapping DCs present for Daddy ((or whoever) for Christmas Eve? And very carefully put it under the tree for tomorrow.
Or just get them involved in preparations - 18 months could probably spoon (with a teaspoon!) the mincemeat into pies while you roll the pastry tops. Or dip things into flour or breadcrumbs. Or get things from the fridge/low cupboards like the carrots to peel (and they will be helping to get ready for Rudolph) or the big pot or the wooden spoon you need for mixing.
If you have no big jobs to do, and town isn’t manic near you, go in for a coffee and cake visit (and maybe a couple of small things that don’t matter if queues are too bad) and look at the lights and the people and the choirs.
Or go to a Christingle service in a local church.
Draw a picture to leave for santa with the stocking to say thank you.