Sync ipad to iPhone
Not all apps on iPad are on iPhone
iPad, iPadOS 16
Not all apps on iPad are on iPhone
iPad, iPadOS 16
Apps installed on your iPad are not necessarily automatically installed on your iPhone - or vice versa. Similarly, Apps themselves are not always available for both platforms - as the respective App Developer has not released a version for both.
For those Apps that are available for both iPad and iPhone, you can configure your devices to automatically install the App on devices when purchased:
Settings > App Store > [Automatic Downloads]
You should note that these settings will only cause Apps and App Updates to automatically install when initially purchased. Others can be manually installed from the App Store.
Perhaps consider that you might not actually want all Apps to be installed on both platforms. Also remember that not all Apps will even be available for both platforms.
As for synchronising data between devices, for Apps that support synchronisation via iCloud, this must also be configured for both devices:
Settings > [Your Name / AppleID] > iCloud > [Apps Using iCloud] Show All - enable services and Apps as required
Sync ipad to iPhone