Hi, I am curious about automatic update.

Settings for the iOS App Store allow for user agreement or size limits.

Settings﹥App Store﹥[ᴄᴇʟʟᴜʟᴀʀ ᴅᴀᴛᴀ] App Downloads﹥

Alternatively, you may disallow the App Store app from using cellular data (only access when on Wi-Fi).

Settings﹥Cellular﹥[scroll down to the ᴄᴇʟʟᴜʟᴀʀ ᴅᴀᴛᴀ app list] App Store﹥Off

Heyo,

iOS update incoming, please stand by… :-) but, seriously I understand your storage anxiety. Take a read of this Set up and use Bluetooth accessories on iPhone - Apple Support

Your friendly neighborhood 

I would think so.

I’m on Wi-Fi most of the time, except when driving, so I wouldn’t notice anyway.

I do not know if I have apps with very large updates, to notice a difference first hand.