I've fantasised about this! I'd make myself a stocking of small presents: luxury shower gel or soap and body cream, a massage brush or mitt, a face pack, nail polish and cuticle oils etc, maybe some new makeup, a really good, easy to read novel or two, a book of poetry, a notebook, pens, lots of my favourite snacks, maybe new PJs and soft socks or loungewear, a candle, some bulbs or seeds to plant.
I'd get in food I love, blitz the house, clean bedding and towels.
Then wake up on Christmas morning, feed the birds, put on some beautiful carols, make fresh coffee and have breakfast, then take a long luxurious bath, with favourite music playing, taking time for scrubs and face masks and massage oils and hair treatments. Get dried and dressed in new loungewear, then take the new notebook, light a candle and makes some lists or plans to look forward to in the year ahead. Not sensible resoutions, but fun stuff. Places I want to visit, from days out to holidays abroad. I'd make a list of things I'd love to do - research when bands I love are playing or shows and exhibitions I want to see open, or find out about workshops, summer schools and classes in subjects I want to try. Also small things - recipes to try, ways to remodel the house or garden. Any project that excites and energises.
After that I'd go for a walk, whatever the weather, just to get some fresh air and look at the sky and the trees. Maybe go to a church service if I fancied it. Call family or very close friends on Zoom. The rest of the day, I'd watch some favourite seasonal films and read the novel, plant the bulbs or seeds I'd bought and make some good food.