Carbon fiber heating cord?

Question

Do it yourself

Hello. I look at ali carbon fiber cords, and according to the reviews it turns out that with a cross section of 1-2 mm the shell is rigid. Can anyone take and tell the elastic option?
https://ru.aliexpress.com/item/20M-12K-33Ohm-Infra... I
understand a little less than zero in physics, so advice is required. I want to attach the cord to the sleeves of a T-shirt, the estimated area is 400 sq cm. Operation at sub-zero temperatures, how long the cord may be needed to maintain an acceptable body temperature and for minimal electricity consumption, well, how much battery is needed for 12 hours of work, for example.))))
In short, I want dofiga, I will be glad if at least someone answers something.))