It's something that a lot of people have been quietly doing for years - either giving an activity to do during the day to keep DCs occupied, or else giving new PJs (and maybe some other bits) at bedtime to help persuade DCs to go to bed quickly on Christmas Eve.
We use a cardboard box, that holds Christmas decorations most of the year.
The family copy of "Twas the night before Christmas" and DD's stocking are part of it. And DD's plastic plate and glass (which are over 10 years old) with a Santa picture - which she puts Santa's snack on.
And the whole family gets new PJs - but that is as much because it is a useful time of year that we could do with a new pair.
The only indulgent thing is a naice hot choc each for us all, and a lush festive bath bomb each for DD and I.
In our case, it helps to lay out the stocking etc, and then signal to DD (with aspergers, so routine and signals are important) that its time for bath and bed. So she has her nice bath, new pjs, and into bed for the story.
It works for us, as we'd generally spend on most things anyway, and lots are re-used over and over. But it does seem to have become a "big thing" for lots in the Facebook and Instagram era.
As with all things Christmas (and in life generally), don't feel you need to do it if it doesn't suit your family. But it could be nice if it does work for you.