please help me for how to smooth rotating animation like The body bones bend according to the movement trajectory.

how to smooth rotating animation like The body bones bend according to the movement trajectory?

i want to add flying or swimming serpent like mob. but i don't know the better solution.

I don't want to use the geckolib plugin, I want to use the Java entity model, but if you have any tips for geckolib entity models, I would appreciate it.