From a top-level perspetive, you need to differentiate McKinsey from the others.
While Bain, BCG and other top consulting firms have their personal fit interviews as you know them from any other company with structured recruiting processes, McKinsey took it on a completely different level with the dedicated McKinsey Personal Experience Interview (PEI).
That's really an interview format of it's own and requires in-depth prep. The good news for you is that most candidates severely underestimate the complexity and time required to get the PEI right, so it's an awesome opportunity to really stand out from the crowd for those who take the time and energy to prepare accordingly (and it contributes to ~50% of your overall interview evaluation). Specifically for the PEI, I have a separate blog with loads of FAQs on that (https://pei.consulting-case-interviews.com/blog/); of course feel free to contact me for one or several coaching sessions on that to really excel on the PEI part.
For the remaining consulting firms, the most important general idea is to present yourself in a structured, top-down approach and highlighting those aspects which potentially make you a good fit for the respective consulting firm. So from a global perspective, I'd recommend having a story line ready on why the next logical step should be consulting, based on your previous experience, and for each experiences you should be able to highlight your achievements and learnings which are relevant for consulting.
(Note: I leave away BCG real life, because it's not really a personal fit interview from my perspective, but also covers subject-matter related topics)
Hope that helps - if so, please give it a thumbs-up with the upvote button!