This is something you should explore with a conference chair. I'm not especially familiar with any "hierarchy" other than "chair" and "member", but suspect that, where it exists, the definitions and requirements differ.
A PC chair, of course has a lot of responsibility, both in organizing the program and in finding other members, It can take quite a lot of time and effort unless you already have a large set of collaborators and others in your field who know and respect you. I assume that position is invited by the Conference Chair.
I also don't know what effect it will have on your professional standing. How is "Senior PC member" a bonus over just "PC member". Both contribute and show activity in the profession. Chair is a step beyond, of course.
But if the Conference Chair of a given conference rotates among a fairly close set of people, then get yourself associated with them and known to them. Offer to help. Offer ideas for improvement, though carefully. But just saying you want to be more involved will probably be enough. Finding willing people is a major task.