How to access iphone
I need to access my contacts on my stolen iPhone & change the passcode on my stolen iPhone
iPhone 11 Pro Max, iOS 14
First, you should pout it in. Lost Mode as described here:
If your iPhone, iPad, or iPod touch is lost or stolen - Apple Support
To retrieve you contacts you can restore the stolen iPhone backup to your new iPhone.
Restore your iPhone, iPad, or iPod touch from a backup - Apple Support
If you haven't already created a backup before the iPhone got stolen, then I am afraid they are lost.