How to limit angle with "Aim Constraint" Component

Notes on clamping camera rotation and NOT using .eulerAngles because of gimbal lock:

How to instantly see gimbal lock for yourself:

All about Euler angles and rotations, by StarManta:

https://starmanta.gitbooks.io/unitytipsredux/content/second-question.html

If you just need Camera controls, move up one level:

Camera stuff is pretty tricky… you may wish to consider using Cinemachine from the Unity Package Manager.

There’s even a dedicated forum: Unity Engine - Unity Discussions