Our brother has a iPhone 14. He passed away. We cannot access his phone. What should we do?

I’m sorry for your loss. If you do not know his iPhone passcode there is no possible way to get to the phone’s contents. However, if you know his Apple ID and password you can access is iCloud account, which might have backups and data that he synced to iCloud from his phone.

If you do not know his Apple ID and password you can request access to his account, as described in this support link→How to request access to a deceased family member's Apple accounts - Apple Support.

Once you have access to his Apple ID you can reset the phone to factory settings, disable Activation Lock and use the phone. You can also restore any backups he made to the phone, and sync any data that he saved to iCloud also.

I'm sorry for your loss.

Follow the directions in this link to get help from Apple --> How to request access to a deceased family member's Apple account - Apple Support

Check this link...

How to request access to a deceased family member's Apple account - Apple Support