To find User Manual pages on new and updated features in Unity 2018.3, click on the link above or search for “NewIn20183”.
This lists User Manual pages containing Unity 2018.3’s:
To find out more about the new features, changes, and improvements to this Unity version, see the 2018.3 Release Notes.
If you are upgrading existing projects from an earlier version to 2018.3, read the Upgrade Guide to 2018.3 for information about how your project may be affected.