The way I sync apps is through iCloud.
On your old iphone go to settings > at the top of the list is your personal account > icloud
Check that the apps on your old iphone are set to 'On'
Do the same with your new iphone.
Now go to settings > your personal account > itunes & app store
Under 'Automatic downloads' switch 'App updates' and 'Apps' to 'On' on both devices
I noticed that you were using iOS 12 when you posted your question.
I would upgrade to iOS 13 because using old OS can create issues
It might be helpful to automatically update your software. Go to settings > general > software update > automatic updates and switch to 'On'