I bet you’ve never heard of the Angular Update Guide. For some reason, it’s not very well advertised even though it’s part of the official Angular documentation.
To get the guide head to https://update.angular.io/
The guide explains all the changes that have occurred between any two versions of Angular. Just enter the version you are using and the version you want. The Upgrade Guide will do the rest.
In my experience, the Upgrade Guide is very thorough. Too thorough really. The list of changes often looks daunting. In practice, I’ve only ever needed to refer to the guide when something broke. I’ve never had to go through the full list.