Photos - Batch rotate images
I've been sorting some 20,000 images in my Photos library into various albums. I've found that a fair number of scanned 35mm negatives are rotated 90° or 180°. Is there a way, either in Photos or using a third party app, to select a batch of images and rotate them in 90° increments? If Photos cannot do this, please suggest an app that will. I've checked the App Store using various phrases but nothing seems to come up. The app doesn't need to be a one-trick pony, just need that rotation is among its editing features.
Thank you
Tod
iPad mini, iOS 12