Good observation - it also reflects topics increasingly present in the client work. While at McK, I used to give cases related to sustainability - I can't reveal any details here but in terms of preparations, I would familiarize myself with topics such as: energy (incl. various sources, conversion, storage, improving energy efficiency), raw materials (sourcing, recycling), use and pollution of air, water land.
Try to take a holistic view - without going too deep into technology but also including infrastructural, geopolitical and behavioral/social aspects. There are many publicly available resources available but to get more into consulting mindset you can try reading through some reports prepared by McK and other firms (e.g. on decarbonization).
I'm happy to work 1-on-1 on these topics if someone feels like they would like to address them more specifically.