Hi Kunal,
For SC/Ops-related roles (and DHL is definitely one of those), my suggestion is to focus on two things:
1. Strategy Basics: you should be able to handle market sizing/entry, profitability, investment-related cases. I wouldn't focus too much on, say, M&A / PE
2. SC/Ops Specific Knowledge: you should get very deep on Ops and Cost Cut cases, getting familiar with concepts like Net Working Capital, Utilisation/Efficiency metrics, Operating Leverage, Total Cost of Ownerships, etc.
DHL Consulting has published a few cases on PrepLounge, so start from there! On the role play section for in-house consulting, this is typically a question where you mimic a real-life situation. E.g., "You are in the team room with your manager and you should discuss how to set up the analysis for this specific problem: ..."
Best,
Tom