How to preserve Lead Creation Date, UTM parameters, and custom fields during Lead Conversion?

How to preserve Lead Creation Date, UTM parameters, and custom fields during Lead Conversion?

We are optimizing our MQL journey. When converting leads to contacts/deals, we need to ensure that the original system Lead Creation Date and UTM tracking parameters (Source, Medium, Campaign) are not lost or archived, as our teams require them for accurate ROI and velocity reporting. What are the best practices or custom mapping workarounds to ensure all historical marketing data flows seamlessly onto the Contact and Deal records post-conversion?