I don't know the answer to this question, however I love the question cannot wait to see the feedback.

Easy, just Google! There are scads of sites with ideas! Here is a sample:

https://www.pinterest.com/pin/234327986835477348/

https://www.pinterest.com/susielala/elf-the-movie-decorations/

https://www.pinterest.com/pin/561261172282583723/

https://youtu.be/WFUYNjxkIew

And if you want to buy stuff, Amazon is your place.

https://www.amazon.com/slp/elf-movie-decorations/sxw2pvqe8sxw8us

Could you post a photo a screenshot of the room you are asking about? Having a visual might be helpful to be able to offer the best guidance .....to a help find the best suggestions or design solution for your need.

I would get a picture of the room and use as inspiration. You can do fake gingerbread out of cardboard. If you post a photo of the room you want, maybe you can get some tips on easy ways to mimic.

Which room are you thinking of from the movie?

https://www.hometalk.com/44195648/winter-wonderland-for-pennies

Winter Wonderland For Pennies!