Apple id

Not sure what you did, exactly then, because there's no way to log out of the App Store directly through the App Store App.

You would have needed to go through Settings ➜ Apple ID ➜ Media & Purchases.

And in that case, all you did was gain access to his account for purchases and subscriptions, but he does not get anything from your device. You will, if you downloaded something, have locked out your own Apple ID for 90 days from there.

Nobody can take pictures remotely, but depending on exaclty what you did, they may be able to access other things beyond.

You should never log in with someone else's account on your device, as may lock out your account for 90 days.

If you explain exactly what you did, where on your iPhone you signed in with this other Apple ID, someone may be able to explan the repercussions of that action for accurately.