Recovering Photos from lost phone

Expanding a bit on what Mac Jim ID said, If you don't use iCloud Photos, but you did have Settings>Apple ID>iCloud Backup turned on, then you may be able to recover data from the last 30 days or so, but you would need to look at the date of the backup to be sure it's from before you lost the images. You should look here:

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

This what you do when you buy a new phone, so this backup, if you have it, requires you to erase everything on your phone and replace it with the backup.

If you don't keep your own backups to an external drive, then there really isn't any place else to look.

You cannot retrieve photos remotely from the iPhone itself

Any photos that were not synchronized to iCloud Photos, stored in iCloud backups, or otherwise stored some place other than just the phone, are gone.

Sorry, but not if they were not stored in iCloud or there is a backup file in iCloud that contained those photos.