This article explains how to turn on automatic updates for your iPhone and iPad, so your devices can automatically patch apps, install the latest versions of apps and games, and sync new purchases across all your devices with a single download. These instructions apply to iPads with iPadOS 13 and later and iPhones with iOS 9 and later.
How to Enable Automatic App Updates on iPhone (ON)
The automatic app update feature eliminates the need to download dozens of updates on each of your devices. Once enabled, your iOS devices will download updates to all apps as soon as they are available.
Open the Settings app.
Tap App Store in the Settings sidebar in iPadOS 13 and iOS 13 and later, or select iTunes & App Store in the sidebar in iOS 12 through iOS 9.