how to transfer data from stolen iphone to new iphone

You don't. If you made a backup kup of the phone before it was stolen, you can recover your data from there.

Restore your IPhone from a backup -

Restore your iPhone, iPad, or iPod touch from a backup - Apple Support

If you have not regained possession of the stolen phone, there's no way to transfer data from the stolen phone to a new one.

You may be able to restore data from backups that you made before the old phone was stolen, or by connecting the new phone to iCloud. (If you were using iCloud Photos on the old phone, then the master copies of your photos are in iCloud, from where they can be synchronized to a new phone.)

Are you saying that you recovered the stolen phone and it is operating normally now?

If not......do you have a recent backup of the stolen phone on iCloud or a computer?