How do you go from a product marketing IC role to a leadership role?

This is a really hard question as it varies from company to company, and your specific situation within that company. The short answer and what's worked for me is -

1. Be willing to do the things that others won't do

2. Prioritize execution over strategy

a combination of those two things will help to make yourself invaluable, and people will naturally start seeing you as a leader. Of course, there's more to it, like

1. you have to let your management team know that you want to be in a leadership role. don't be shy about it.

2. work on your executive presence

3. learn about the business all-up - what are other teams prioritizing and how can you slot yourself into those priorities (aka give yourself visibility)

4. actively consult feedback from peers and leaders

I'd also think more deeply about what leadership actually means to you. Does leadership mean you want to build and lead a large team where you act as the coach? Or does leadership mean you move up in title as an IC where you still have strong impact and influence?