She looks quite ill - if she is outside currently, could you bring her inside, somewhere warm, and quiet? After she has acclimated to being inside, can you determine if she is eating, and drinking and if she is producing droppings, if yes to the latter, post a picture here.
From my limited observations in the picture you posted, it appears she is attempting to maintain her body heat and has an obvious distended crop. The penguin-like stance she has is indicative of a reproductive disorder which is a common problem in older hens.
To further determine what might be the problem, a thorough physical examination would be a good start. You can find information pertaining to doing a physical exam here:
https://www.merckvetmanual.com/exot...ltry/physical-examination-of-backyard-poultry
I would be particularly focused on her crop and abdominal area and noting whether the areas are hard, soft, or liquid-like, and how far distended they hard. If she is not eating, or drinking much, supplemental tube feeding would be suggested until her problem can be established. Here is some info on that topic:
https://www.backyardchickens.com/threads/tube-feeding-ducks-updated-5-7-2020.1211994/
Getting a good baseline weight on her, and continue weighing each day to determine how much, and if she is losing weight would be another good measure to help fiqure out her current state of health.
