I think there’s no way to automactically turn on shift lock without using shift button. Although, you can just press shift to turn it on, and this is the only and the most efficient way to do this. If we can turn on shift lock without the shift button than why it is called “ShiftLock”? Thanks for asking this question.
I believe you have to fork the current camera scripts and read through it for proper comprehensions of its functionality. If you have found the shift locking mechanism, just rewrite it to the forked scripts.
To answer your question, there’s a code sample on the Camera Manipulation article that act similarly to shift lock. There’s no forking of the camera scripts needed, just create a LocalScript into StarterPlayerScripts and copy the code from the Over-the-Shoulder section.