How do I add photos to hidden folder with iPhone 7, when I use share button I don’t see hide

The link that I posted for you shows how to hide a photo in iOS 13. I don’t think that you are using the Apple built in photos app. The icon in the red box is the photos app. Hiding photos only works with this app.

I think I know what you are doing. You are tapping on More in the Options. Just tap on the share icon. That is the icon that looks like a square with an arrow pointing up.

Select a photo and Tap the Share icon and you should see what I posted in the screenshot. If you have to, Tap Done at the top left and that will get you back to the share sheet that I am showing.

Are you running iOS 13 like your tag line shows? Did you swipe down far enough? Take a look at this.

https://www.imore.com/how-hide-images-photos-app

The model of the phone doesn’t matter, it’s the iOS that would have some bearing on it. I’m running iOS 14 and this is what I see in my share sheet in the photos app.

Do this and post back. Go to Settings>General>About>Version. That will show you which iOS version you are running.

I’ve never seen anything like that before. Are you using the built in Photos app? Do you use iCloud Photos?