Seperate her in a see don't touch area if possible. Let her get through molt. She may be having some hormonal upset.
My experience my not be helpful or hopeful, but it is similar.
I had a hen who started doing this at around 3 years old. She too, was a very friendly girl. Beautiful and a good layer. She was even a favorite with my older rooster.
I had two roosters with my flock. Not push over roosters, but "keep the flock in line" roosters.
She fought with them, tried to knock them off "her" pullets. The other hens were terrified of her, with the exception of her mother, her sister, and daughter. Oddly enough, she never tried bullying them.
It got so bad that eventually I rehomed her, along with her small family. I hated to do so, but I tried separating her, and even moved her to another coop, with the other rooster. She and her family are doing well at their new home, and my flock is calmer.
I wish you the best of luck! I hope things work out for you and all your hens.