PWC consulting interview formats can vary quite significantly across geographies, based on feedback from some of my past coachees - if you could share which office, will be easier to give specific advice. Alternatively, always a good idea to check with local recruiting team / HR, as some coaches already highlighted.
Generally speaking, format will usually be candidate-led - as Christian also mentioned. However, the degree can vary based on interviewer style. While some let you lead 100%, others tend to jump in with more questions and keep it a bit more conversational.
Re prep time - typically there won't be too much of that in a 1h case format. You will usually get an either short written (common for PWC) or verbal problem briefing, and at times exhibits may be shared (esp. true for many org-related topics) - then, just like typical candidate-led settings, once gone through that, you can take a few min to verify the understanding, ask clarifying questions and develop an initial case framework. But again, exact format & timings can be quite office-specific.
Feel free to PM, if you have follow up questions.
Hope this helps.