Automatic update is a great feature
which Apple introduced on iOS 7. When turning on automatic app updates, it
automatically updates to the new version of any apps when connected to Wifi and
cellular data. This is great for most users to stay up-to-date without manually
doing anything. 

Here’s a simple steps on How to disable automatic app updates and downloads on iPhone/iPad running iOS 10.3.2/10.3.1 or below.

But some users like to stay to the previous version and always
want to disable automatic downloading app updates on iPhone/iPad due to some
reason. Because you can’t downgrade back to previous version once you have
updated the app. So doing this you always have an option to stay in the older
version or can update to the latest version anytime you like.
Here’s a simple steps on How to disable
automatic app updates on iPhone/iPad and iPod touch running iOS 10 or later or below

How to disable automatic app updates on iOS 10
Step 1:  Go to Settings > App and
iTunes Stores.
Step 2:  Tap on the Updates button to
toggle it off.
Along with that you can also disable automatic
downloads for Music, Apps and Books as well.
That’s all. You are done!
Note: Automatic Downloads are not
available while you are in Low Power Mode.

So simply turn off Low Power Mode when
you wanted to disable or enable the automatic downloads.