MAC book pro automatically shuts down

Does it turn second time?

If yes,

Reset PRAM:  Reset NVRAM or PRAM on your Mac - Apple Support

Settings that can be stored in NVRAM include sound volume, display resolution, startup-disk selection, time zone, and recent kernel panic information. The settings stored in NVRAM depend on your Mac and the devices that you're using with your Mac.

Reset  SMC:   How to reset the SMC of your Mac - Apple Support   Choose the appropriate method.

Quote:

Resetting the system management controller (SMC) can resolve certain issues related to power, battery, fans, and other features.

Startup in Safe mode. https://support.apple.com/en-gb/HT201262

To leave Safe Mode, choose “Restart” at the bottom.

Quote:

     Safe mode prevents your Mac from loading certain software when it starts up, including login items, 

     system extensions not required by macOS,

     and fonts not installed by macOS. It  also does a basic check of your startup disk, 

     similar to using First Aid in Disk Utility. 

     And it deletes some system caches, including font caches and the kernel cache, 

     which will be created again automatically as needed.

If your Mac doesn't start up all the way

https://support.apple.com/en-us/HT204156

Contact Apple Support.

  Click inside the box to choose an option.

  https://getsupport.apple.com/?caller=kbase&PGF=PGF63005&category_id=SC0245&symptom_id=23362