I set up my new iPhone 11 without transferring app from iPhone 6 because the Wi-fi wasn’t stable enough. Can I do that later (when I find good Wi-fi) or do I need to reset and do it from the beginning again?
iPhone 11 Pro Max
You need to restore a backup of the old phone. But this will replace everything on your phone, so if you have added anything it will be lost. See-->Restore your iPhone, iPad, or iPod touch from a backup - Apple Support
You need to restore a backup of the old phone. But this will replace everything on your phone, so if you have added anything it will be lost. See-->Restore your iPhone, iPad, or iPod touch from a backup - Apple Support
Set up new iPhone to transfer app after initial set up
