Hello Lowtide,
Welcome to Apple Support Communities!
We want to help you edit your photos to add a date or caption on iOS.
Since this isn't a build-in feature of iOS, you might find an app in the App Store that fits your needs. Try here:
"How to get apps
- On your iPhone, iPad, or iPod touch, open the App Store app.
- Browse through the Today, Games, Apps, or Arcade tabs to find apps you like. Or tap the Search tab to look for something specific. If you find a game that says Arcade, subscribe to Apple Arcade to play the game.
- Tap or click the price or Get button. If you see the "Open" button instead of a price or Get button, you already bought or downloaded that app."
This Apple Support page has the full details: Download apps and games on your iPhone or iPad - Apple Support
We welcome and encourage you to submit this feature request here: Product Feedback - Apple
We hope this helps to edit your photos.
Cheers!