How can you rotate iPhone 12pro max screen so when I use maps in portrait mode the charging point would be at the top

On my iPhone 7 I could use Google maps and turn the phone upside down and charge it whilst in holder in car. I can not find how to do this on iPhone 12 Pro Max. All the advice is just about pulling down top right of screen and unlocking screen rotation this does not allow you to rotate fully. My son has my old 7 and have checked and you can still fully rotate 360degrees on it so why not on the 12