Strategy: Express gratitude, validate that you take their commitment seriously, and request a specific, reasonable extension with a clear rationale.
Script: 'Thank you so much for the offer; I am genuinely honored by the team's confidence in me. Because this is a major long-term career decision for me and my family, I want to ensure I review all contract details, benefits, and equity terms thoroughly. Forty-eight hours is a bit too tight to do proper due diligence. Would it be possible to extend the decision deadline until next Tuesday at 5 PM? Having those few extra days will give me the time needed to finalize everything with complete confidence, and I look forward to giving you a well-considered answer.'