Your friend is most likely being managed out, and I doubt it's just about the leadership thing. If I had an otherwise good employee who was just underperforming in leadership, I would try to coach them, not threaten to put them on a PIP. The leadership piece is probably singled out because it's easier for the manager to document, and/or an area the manager thinks your friend will not improve in, thus making it possible for her to be let go.
If I were your friend, this would be my strategy:
1. Start looking for a new job yesterday. My goal would be to get a new job before my manager has grounds to let me go. Otherwise the likely outcome is no job, and no positive reference from my previous employer.
2. Ask my boss what good performance looks like in all the areas where I need to improve. The manager might be evasive about this. Which is one reason I would also...
3. Involve HR. I would not under any circumstances complain to HR about my boss, explain why boss's expectations are unreasonable, or otherwise expect them to save me from the situation. I would tell them I want to improve, and what kind of support can they provide?
4. I would do everything my boss asked, even if I thought it was hard or stupid. I would document absolutely everything I did to comply and put it in front of my boss and HR. I would keep in mind that my boss is actually hoping I'll push back and give a bunch of Reasons I can't comply, because if I do that, she can say, "I set the expectations, she refused to accept them and failed to meet them," and proceed with getting rid of me.
Hopefully all of that would buy me a few months to find a new job. If I was successful and got off the PIP path, I would still keep looking for a new job.
ETA: Sorry, re-read and saw this person is not on a PIP yet. Doesn't change my thoughts on this much.